Bitaxe – OTA Update Failed Mid-Transfer / Partition Switch Error

Wait 5 full minutes after the OTA appears to stall before doing anything destructive. ESP-IDF's `esp_https_ota` post-download SHA verification can take 60-90 seconds on a slow flash, and the OTA may complete silently after the visible progress bar froze. If the OLED comes back on its own, run `Test Mining` from the dashboard for 5 minutes to confirm hashrate, then retry the update on a stable network.

Hard power-cycle from the breaker / outlet. Unplug both USB-C and the DC barrel jack (or USB-C only if that's your only power). Wait 30 full seconds for the 5V rail capacitors to drain. Plug back in, wait 60 seconds for AxeOS to fully boot, then check `http://bitaxe.local` or your reserved IP. ESP-Miner's bootloader auto-rolls back to the last-known-good OTA partition if the new one fails CRC validation. About 70% of stalled OTAs recover on this single power-cycle.

Look for the AP-config fallback SSID `Bitaxe_XXXXXX` in your phone's WiFi list within range of the miner. If it appears, the firmware booted but NVS lost WiFi credentials. Connect a phone to that SSID, browse to `http://192.168.4.1`, re-enter your WiFi password and pool URL. This is soft-recovery — no flashing needed, takes 2 minutes. Save credentials in a password manager next time.

Verify your home network is still 2.4 GHz. Bitaxe ESP32-S3 supports ONLY 2.4 GHz WiFi — no 5 GHz, no Wi-Fi 6E. If you switched routers / mesh / bands mid-update, the OTA may have completed but the new firmware can't reconnect. Re-enter the AP-config flow (Step 3) and connect to a 2.4 GHz SSID specifically.

Hard-reset NVS via 5-second `RESET` hold. Some AxeOS builds support an NVS-clear gesture: hold the `RESET` button for 5+ seconds while powered. This wipes NVS without touching OTA partitions, forcing AP-config mode on next boot. Useful if NVS state is corrupt from a half-completed migration. Re-enter WiFi and pool config when the AP appears.

Use the Bitaxe Web Flasher to re-install factory firmware while preserving NVS. Open bitaxe.org/flasher in Chrome or Edge (Firefox/Safari do NOT support WebSerial). Connect via a known-good USB-C DATA cable. Click `Connect`, select the `USB Serial Device` / `ESP32-S3` port. Pick your exact model from the dropdown. Click `Install`. CRITICAL: leave `Erase Flash` UNCHECKED — this preserves NVS so WiFi creds, pool config, and ASIC calibration survive recovery. Total time: 30-60 seconds.

`esptool.py` re-flash from the command line for full control. `pip install esptool`. Force ROM bootloader: unplug, hold `BOOT`, plug USB-C, release `BOOT` after 3 seconds. Run `esptool.py --chip esp32s3 --port COMx --baud 921600 write_flash -z 0x0 esp-miner-factory-<model>-vX.Y.Z.bin` — substitute correct factory `.bin` from github.com/skot/ESP-Miner/releases. The combined factory image writes bootloader (0x0), partition table (0x8000), and factory app (0x10000) in one shot. Terminal errors are vastly more informative than the Web Flasher.

Reset `otadata` to force factory boot if rollback won't engage. If the symptom is repeated `boot: Fall back to factory` on serial console or the bootloader is stuck pointing at a corrupt OTA slot, erase only `otadata`: `esptool.py --chip esp32s3 --port COMx erase_region 0xe000 0x2000`. The 0xe000 offset and 0x2000 size match the standard ESP-IDF partition layout. After erase, reset the chip — it boots from the `factory` slot. You can then OTA back to the desired version from a clean state.

Download the EXACT correct factory `.bin` for your hardware. From github.com/skot/ESP-Miner/releases pick: `factory-gamma` for Gamma/GT, `factory-supra` for Supra, `factory-ultra` for Ultra, `factory-max` for Max. Bitaxe Hex uses the multichip-fork factory image from shufps/ESP-Miner-NerdQAxePlus if running that fork, or the Hex-specific image in the main repo. Cross-flashing variants boots ESP32 but traps `asic_init_fail` because the wrong ASIC driver talks to wrong silicon — looks bricked, isn't, but requires re-flash with correct image.

Validate flash address layout before writing custom binaries. Standard ESP-Miner partition table: `bootloader` at 0x0, `partition_table` at 0x8000, `nvs` at 0x9000, `otadata` at 0xe000, `phy_init` at 0xf000, `factory` at 0x10000, `app0` at ~0x110000, `app1` at ~0x210000. If flashing partitions individually instead of the combined factory `.bin`, get those offsets right or you overwrite NVS and lose WiFi creds. The combined factory `.bin` writes everything except `nvs` — that's why it's the safe default.

UART recovery if USB-C is also dead. Bitaxe exposes labeled `TX0`, `RX0`, `GND`, `EN`, `IO0` test points on the PCB. Solder pin headers (or use spring-loaded pogo pins). Connect FT232RL or CP2102 USB-to-3.3V-UART adapter: adapter `TX` → Bitaxe `RX0`, adapter `RX` → Bitaxe `TX0`, common `GND`. Power Bitaxe via its normal 5V input (not the UART adapter's 5V — avoids backfeed). Short `IO0` to `GND`, briefly pulse `EN` to `GND` (hardware reset), release `EN`, then release `IO0`. Run `esptool.py --port <UART-COMx> --chip esp32s3 --baud 460800 chip_id`.

Drop UART baud rate if 460800 fails. UART signal integrity over flying leads is much worse than a clean USB trace. Try `--baud 230400`, then `--baud 115200`. `write_flash` at 115200 on a 16 MB part takes 6-8 minutes — be patient, don't move the wires, don't unplug. The slower baud is more reliable on noisy hookups.

Read NVS before any destructive recovery to preserve WiFi creds and pool config. `esptool.py --chip esp32s3 --port COMx read_flash 0x9000 0x6000 nvs-backup.bin`. After re-flashing factory, write NVS back: `esptool.py write_flash 0x9000 nvs-backup.bin`. This preserves network configuration across a full erase-and-restore. Particularly useful when you don't remember the long auto-generated WiFi password from your AP-config setup three months ago.

Cross-flash an alternative firmware to confirm hardware health. From bootloader (USB-C or UART), flash a different ESP-Miner fork to confirm ESP32-S3 + flash chip are both healthy. For NerdQAxe-style multichip Bitaxes try shufps/ESP-Miner-NerdQAxePlus. For NerdAxe try BitMaker-hub/ESP-Miner-NerdAxe. If any boots and shows native UI, hardware is fine and original failure was firmware-side. Returning to your preferred stock build is just another flash cycle from a known-good baseline.

Check SPI flash health with `esptool.py flash_id` and full erase test. Run `esptool.py --chip esp32s3 --port COMx flash_id` — should return manufacturer ID matching MFG 0xc8 (GigaDevice) or 0xef (Winbond) and `Detected flash size: 16MB`. Then run a full `erase_flash` and re-program. If the erase fails partway through with `Timed out waiting for packet header` or hangs at a specific sector, the SPI flash chip itself may be wearing out — that's Tier 4 territory because it requires desolder + replace, not a home fix.

Stop DIY (Tier 4) when: UART recovery per Step 11 also returns `Failed to connect`; OR `esptool.py erase_flash` consistently fails at the same sector (SPI flash wearout); OR ESP32-S3 module shows physical damage (scorching, cracked epoxy, swollen caps, burnt smell); OR you reverse-polaritied 5V DC input and the 3.3V LDO is dead; OR USB-C connector pads have torn loose past hand-reflow; OR your own hot-air reflow attempt made things worse. Ship to D-Central — we pioneered the Bitaxe ecosystem, built the original Bitaxe Mesh Stand, developed the first Bitaxe + Bitaxe Hex heatsinks, and stock ESP32-S3 modules + 16 MB SPI flash + USB-C connectors for exactly these recoveries.

D-Central bench process: run the full diagnostic protocol on bench fixtures with a known-good 3.3V UART harness and a clean USB-C tester. If SPI flash is the culprit, hot-air-swap the GD25Q128 / W25Q128 module, re-flash factory image, burn-in 4-6 hours at nameplate hashrate. If ESP32-S3 module itself is dead, swap with a pre-flashed replacement matching your variant. Replacement USB-C connectors, lifted-pad jumpers, burnt LDO replacements all happen on the same bench. Turnaround typically 3-7 business days.

Ship safely. ESD bag (anti-static), foam cradle inside a rigid box, note inside describing the failure (which AxeOS version you were OTA'ing from → to, whether USB-C and UART recovery were attempted, whether the OLED shows anything during boot). If you soldered UART headers onto the test points, mention it — we either remove them or leave them per your preference. Include any heatsink and fan accessories so we can full-stack bench-test. Canada Post small-parcel or UPS Ground; we receive at D-Central HQ in Quebec and crack open within 48 hours.