DCENT_OS AM3-BB Recovery

Safe recovery order

Cut hash power / AC if the electrical disposition is unknown. Keep fans quiet; do not blast.
Prefer microSD recovery. The AM335x BootROM probes SD before eMMC/NAND on most Bitmain BB boards — no jumper.
Do not raw-write NAND. Never dd, flash_erase, or nandwrite (including mtd4). NAND install/revert is disabled until dated live /proc/mtd evidence is admitted.
If SD boot fails, use UART (115200 8N1, 3.3 V TTL only — not RS-232). JTAG is last resort.

1 · microSD rescue (default)

Admit the exact am3-bb / am3-bb-s19jpro SD payload on a trusted host with scripts/safe_extract_am3_bb_payload.py. Do not tar xf an unadmitted archive.
Format the card FAT32, label boot. Write MLO first, then u-boot.img, kernel, DTB, and the admitted ramdisk.
Power the miner off, insert the card, power on. If SD boot does not trigger, hold the IP-Reporter button at power-on until the control-board green LED blinks.
Complete the first-boot wizard on the LAN before SSH. This page never shows a login or password.

The SD tarball is not a NAND/sysupgrade package. Do not flash it to eMMC/NAND.

2 · Inspect over the LAN (after wizard SSH)

From a computer on the same network, connect as the account you provisioned in the wizard (this page does not name a default password):

ssh <provisioned-user>@<this-miner-ip>
hostname
/etc/init.d/S82dcentrald status
/bin/sh /usr/libexec/dcentos/dcentrald-session-latch.sh status

Replace the address with the one in the browser URL bar. Logs: tail -n 100 /tmp/dcentrald.log

3 · UART if SD boot fails

Use a 3.3 V USB-TTL adapter (FT232/CH340). AM335x is not 5 V tolerant. Bitmain BB debug UART is typically a 3/4-pin header near the eMMC: GND / RX / TX / (3.3 V — leave NC). Open a terminal at 115200 8N1, no flow control. Power the miner and break into U-Boot (spacebar in the first second). Capture printenv; force SD boot from U-Boot rather than writing NAND. If you are unsure, stop and contact D-Central — the unit is safer powered down than with a guessed flash.

4 · Do not raw-write storage

If the daemon will not start, roll back by booting the admitted SD image. Environment changes, when they are ever authorized, use fw_setenv only — never raw NAND. am3-bb NAND install/revert remains disabled pending live /proc/mtd evidence.

Do not automate latch-clear or restart from this page. A process exit is not proof that hashboard rails are off.