ASIC Miner Firmware: Updating, Flashing and Recovering Whatsminer and Antminer Control Boards

Firmware is the software the control board runs. It is the operating system of the miner: it holds the miner and pool settings, serves the web interface, offers whatever customisation the manufacturer allows, and usually runs on a variant of Linux. Every miner needs it, and a surprising share of "hardware" faults on the bench turn out to be firmware — wrong version, corrupt recovery, or a locked board. This guide covers what we check and how we flash, for both MicroBT Whatsminer and Bitmain Antminer.

When to update firmware

New firmware generally improves stability and security, and sometimes adds features such as a low- or high-performance power mode. Beyond that, update to the latest available release when:

• the unit is malfunctioning and you have not yet found a hardware cause;
• you install a new power supply;
• you install a new control board — this may need an SD card the first time, since the board may not accept a network upgrade until it is on compatible firmware;
• the manufacturer requires a transition firmware before a bigger jump.

Official downloads: MicroBT publishes Whatsminer firmware on its firmware download page. Bitmain firmware is on the Antminer support site — with a caveat covered below.

Reading the Whatsminer status pages

The Whatsminer web interface gives you almost everything you need before you open the case. On the Status → System page, note the model, hostname (which encodes the control board type), Firmware Version, kernel and miner version, uptime and load average. On Miner Status, the fields worth reading first:

• Elapsed and GHSav — how long the miner has been running and its average hash rate over that period. A short Elapsed with a low GHSav may just be a miner that is still tuning.
• FanSpeedIn / FanSpeedOut — intake and exhaust fan RPM. A missing or wildly different reading points at a fan or fan cable, not a hash board.
• Devices — per-slot Frequency and GHSav for SM0, SM1 and SM2, and the Total. One board well below the others is where to look.
• Status, UpfreqCompleted, EffectiveChips, Temperature — Alive, whether tuning has finished, the chip count the firmware can see, and board temperature. A board showing fewer effective chips than its siblings has a chip or domain fault.

UpfreqCompleted and autotuning

UpfreqCompleted reads 1 once autotuning has finished. In the standard power mode that takes anywhere from 10 minutes to an hour; switching between power modes forces a longer retune. When it completes, GHSav stabilises and each chip is running at its proper frequency and voltage. In Full Power mode, autotune is quicker — typically 5 to 10 minutes — but moving between Low and Normal mode still requires a retune.

Antminer dashboard showing nothing?

On some browsers the Antminer dashboard renders as an empty grey panel at certain zoom levels — the page scales badly and the machine data never appears. Before assuming the control board is dead, change the browser's zoom percentage and reload.

Whatsminer: H616 firmware locks and SD recovery

Recent Whatsminer firmware for the H616 control board adds security features, and with them a one-way door. Once an H616 board on older firmware is upgraded to 20250915.16.Rel2 or later, you can no longer flash the older 20240328 recovery image to it; you have to use the matching recovery, WhatsMiner-SDCard-Image-h616-20250915.16.Rel2.zip. Upgrading to 20260130.12.Rel2 closes the door again: SD recovery back to 20250915.16.Rel2 will no longer work. Keep a copy of every recovery image you use, and check the board's firmware version before you decide which one to burn.

Antminer: the service-pack gap and what to flash with

Since July/August 2024 Bitmain no longer offers the TF Card Service Pack on its website. Flashing a new Antminer control board without the right files has been awkward ever since, so keep the recovery and unlock files you already have. The kit we use:

• an 8 GB microSD card;
• a 32 GB USB dual drive;
• a USB hub if the computer has no SD card slot;
• the contents of the recovery folder copied straight onto the card or drive — copy the files, do not image them.

What the LEDs mean while flashing

A typical Antminer flash takes 10 to 30 seconds. Which lights you see depends on the control board:

If the pattern is anything else — both LEDs staying on, both flickering, red on while green flickers, red only, or no LEDs at all — the flash did not take. The usual causes, roughly in order of how often we see them:

• the SD card is bad;
• the recovery files are corrupt;
• the recovery is for a different control board model;
• the control board is locked;
• the control board itself is faulty.

Locked control boards and unlock files

Newer Bitmain firmware locks the control board: it will not accept a recovery for a different model, a rollback to older firmware, or third-party firmware. To get past the lock, copy the contents of the unlock package for that model onto the drive or SD card and flash that first. Some models need a different unlock file than you would expect — for example the CVITEK_T21 unlock is what flashes an S19k Pro, and the S19 XP recovery is what you use to flash an X5 recovery.

SD card showing a tiny capacity after Balena Etcher?

Writing an image with Balena Etcher (or similar) leaves the card partitioned in a way Windows reads as a fraction of its real size. To restore full capacity on Windows, press Win + X and open Command Prompt (Admin) or Terminal (Admin) — or search cmd in the Start menu, right-click and Run as administrator — then:

• type diskpart and press Enter;
• type list disk and press Enter;
• type select disk 1, where 1 is the number of the SD card in the list — check the size column, because picking the wrong disk erases it;
• type clean and press Enter (repeat once if you get an error);
• type create partition primary and press Enter;
• type format fs=fat32 quick and press Enter.

Disk Management can do the same job — delete the partitions and format — it just takes longer.

Whatsminer: burning recovery cards with PhoenixCard

Whatsminer SD recovery images are written with PhoenixCard, which ships inside the SD card flashing program on the Whatsminer website. Before you pick an image, open WhatsMinerTool: it shows the type of control board each miner is running (H3, H6OS, H616 and so on) alongside its firmware version, and the image must match the board. You cannot flash H3 firmware onto an H6OS board, or H6OS firmware onto an H616.

• Insert an SD card of at least 1 GB into the laptop or a USB reader.
• In PhoenixCard, select the image file, leave the work type on Product, and click Burn.
• Wait for the progress bar to turn green and the output log to show Burn End. A second card reader showing 0 M and a red format card failed line is just an empty slot — ignore it.
• Power the miner off, unplug the Ethernet cable, and insert the card into the control board's SD slot.
• Power on. The control board reads the card and burns automatically: the red LED flashes, and after about a minute the green light comes on. Burning is complete.
• Power off, remove the card, reconnect Ethernet and power.
• Check the error log. If 201-8410 is present, upgrade the firmware through WhatsMinerTool.

Error 201-8410

Seen on M3X-series and older Whatsminers after an SD recovery, 201-8410 means the recovery image's miner software does not support the hash-board chips fitted — the log reads Firmware not support chip 1922, or Firmware is for chip 1920, 1800, 5100, but current is ffff, with 201 Power detect error, can not find config for power P221B alongside it. Upgrading the BIN firmware from WhatsMinerTool clears it. If it will not clear after the upgrade, the control board is faulty.

Aftermarket firmware

Vnish, MARA, HiveOn, Braiins OS+ and LuxOS are the aftermarket firmwares you will hear about most. They exist because they can extract more hash rate and sometimes better efficiency — against a dev fee, typically a percentage of your hashing. The 2025 Cambridge Digital Mining Industry Report put manufacturer firmware at 44.4% of surveyed hash rate, Vnish at 26.4%, proprietary firmware at 17.6%, Braiins OS at 5.6%, LuxOS at 3.3% and ePIC at 2.7%.

We do not endorse loading aftermarket firmware, and we say so plainly for a reason:

• It voids the manufacturer warranty. Loading a separate firmware is enough on its own.
• It can damage the machine. The customisations that raise hash rate also raise stress on the ASICs and shorten board life.
• It can carry malware. The classic case was BeagleBone control boards on L3 and S9 machines: a "firmware" promising a large performance boost, which then spread to other units on the same network.
• It usually costs money. The dev fee is taken from your hash rate, on top of whatever the firmware is doing to the hardware.

Changing hash board frequency on stock firmware

Antminer hash boards can have their stock frequency changed in the board's EEPROM with a tool such as ARC, which raises hash rate on stock firmware without an aftermarket dev fee. A few rules apply: all boards in a machine must be set to the same frequency step, and the frequency is capped by the firmware — a 134 TH S19 XP can be clocked to the 141 TH variant's rate, but no higher. The same warning stands: a higher frequency puts more stress on the ASICs and can lead to premature board failure, so weigh the extra hash rate against the shorter life.

Web login and password resets

If the defaults are refused, someone has set a custom password. Options, from least to most drastic:

• Clear the browser cache (Ctrl+Shift+Del in Edge or Chrome). If the router has handed the same IP range to a Whatsminer, an Antminer and another manufacturer's machine over time, a stale cached login can block you even with the right credentials — periodic clearing avoids it.
• On a Whatsminer, the Restore Miner and Factory Reset options in WhatsMinerTool remove the password and/or the pool settings.
• Hold the reset button on the control board until the LEDs flicker.

Board will not take a flash?

Send us the model, the control board type, the firmware version and what the LEDs do, and we will tell you whether it is the card, the files or the board. Control board and hash board repair for Whatsminer and Antminer is done at our Chicago bench — contact us.