Recovery first. Always. This is the checklist to work through before you flash DCENT_OS — ideally while you are still on the waitlist and there is no image to rush. DCENT_OS is experimental beta firmware: it can brick a miner, cause downtime, and flashing custom firmware can void your manufacturer warranty. The single rule that keeps a bad flash from becoming a dead miner is this: never flash a miner you are not prepared to recover. Everything below is how you get prepared.

The checklist in one line

Before flashing DCENT_OS: pick an Antminer S9 you can afford to take offline, prepare a recovery SD card, confirm you have UART/serial access, back up your current configuration and firmware, and read the install and rollback guides end to end. Do all five before you write a single image.

1. Pick the right miner — an Antminer S9 first

DCENT_OS is in closed beta on the Antminer S9 family (S9 / S9i / S9j) only. S17, S19, and S21 support is in active development and is not flashable yet. So your first DCENT_OS miner should be:

• An S9, not your only earner. Choose a unit you can take fully offline without it mattering to your operation. Beta firmware is for hardware you can experiment on.
• Identify the control board. The S9 shipped with several control board revisions — XIL, BB, CV, and AML variants — built around a Xilinx Zynq 7010 (dual Cortex-A9 @ 667 MHz). The install path is validated board by board, so knowing yours matters. The install guide shows how to tell them apart.
• Confirm it boots stock cleanly first. A miner that is already flaky on factory firmware is not a good beta candidate — fix it (or send it to the repair bench) before you add experimental firmware on top.

2. Prepare a recovery SD card

The S9’s Zynq control board can boot from a microSD card instead of its onboard NAND. That SD-boot path is both how you install DCENT_OS and how you recover if a flash goes wrong — which makes a known-good recovery SD card the most important thing you own during beta.

• Have a spare microSD card (a small, reliable card is fine) dedicated to recovery, plus a card reader.
• Know the SD-boot jumper. S9 control boards select SD boot with the J3 boot-mode jumper (open = boot from NAND, shorted = boot from SD). The install guide covers the exact position for your board revision.
• Keep a stock recovery image ready so you can write factory firmware back to the card at any time. The generic SD card firmware flashing & recovery guide walks through imaging a card and the recovery boot.
• Test the SD-boot path on stock first. Confirm your miner will actually boot from SD before you depend on it for recovery. A recovery method you have never tested is not a recovery method.

3. Confirm UART / serial access (your last resort)

If a flash leaves the board unable to boot from NAND or SD, a UART serial console is how you see what the bootloader is doing and drive a low-level recovery. It is the difference between “recoverable on the bench” and “dead.”

• Get a 3.3 V USB-to-UART adapter. The S9 Zynq debug console runs at 3.3 V logic — do not use a 5 V adapter on it.
• Know the settings: 115200 baud, 8-N-1. These are the standard S9 console parameters; the rollback & UART recovery guide covers the header pinout for each control board.
• Locate the UART header before you need it. Find and label the TX / RX / GND pads on your specific board now, while it still boots normally — not while you are panicking over a brick.

You may never touch the UART. But having the adapter, the settings, and the header located is what turns a worst-case flash into a fixable one.

4. Back up your current configuration and firmware

• Record your pool settings — pool URLs, worker names, and passwords — somewhere off the miner. After a flash you will re-enter these by hand.
• Note your current firmware version and miner model/board so you know exactly what stock you are rolling back to if needed.
• Keep the matching stock firmware file for your model on hand, so a rollback does not depend on hunting for a download mid-recovery.
• Photograph the board — jumper positions, connector orientation, the control board label. Cheap insurance when you are reassembling at 1 a.m.

5. Read the guides end to end — before you flash

When an image is ready for your hardware, do not improvise. Read these first; the rollback guide especially, before the install — so you know the way back before you take the first step forward:

• Roll back to stock & recover a failed DCENT_OS flash (SD + UART) — read this one first.
• Install DCENT_OS on the Antminer S9 (SD card, closed beta) — the step-by-step install path.
• DCENT_OS Heat Mode first boot — getting a quiet, low-noise S9 running once it is installed.
• DCENT_OS beta safety & warranty — exactly what you are agreeing to, including warranty implications.

Some of these guides go live alongside the first public S9 image. If a link is not live yet, that is the honest state of the beta — check the dated beta status page for what is published.

If a flash goes wrong

Work the rollback guide: re-image your recovery SD card with stock firmware, set the boot jumper to SD, and bring the miner back up. If the board will not respond on NAND or SD, the UART console is your next move. And if you cannot recover it yourself, the D-Central repair bench — the same bench that has serviced thousands of miners since 2016 — can help. Recovery support is a paid repair service, separate from the firmware, which is open-source and provided as-is with no warranty.

When you are ready

If you have an S9 you can take offline, a tested recovery SD card, UART access located, a config backup, and the guides read — you are ready for an image when one opens. Join the waitlist and we reach out once, when the S9 image is ready to flash, and join the Discord if you want to compare notes with other testers.

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FAQ

Do I really need a UART adapter?

Not for a normal install — the SD card path handles installs and most recoveries. UART is your last resort if the board will not boot from NAND or SD at all. For beta firmware on hardware you care about, having it ready is cheap insurance.

Can I flash an S19 or S21?

Not yet. Closed beta is the Antminer S9 family only. S17, S19, and S21 support is in active development and ships in later stages. The beta status page tracks which platforms are flashable.

Will flashing void my warranty?

Flashing third-party firmware can void the manufacturer warranty on your miner. DCENT_OS is open-source firmware provided as-is, with no warranty of its own. The beta safety & warranty guide spells out exactly what that means.

What if I brick my miner and cannot recover it?

Work the rollback guide first. If you still cannot bring it back, the repair bench can help — that is a separate paid service, not a firmware warranty.