Recovering a bad eMMC flashed image on NanoPi R2C

FriendlyElec has poor instructions in their wiki and after much trial and error I finally was able to recover and reset the onboard eMMC storage on my Nanopi R2C Plus.

Backstory: I used FriendlyElec eFlasher tool to flash a raw .img file to the onboard eMMC 8GB storage of my NanoPi. This led to an onbootable system. I had to use UART serial to view the errors and debug.

You will need a UART serial connection and putty installed. This quick how-to guide is intended to be ‘cliff notes’ on what I did to get my device back in working order; you will have to teach yourself or search how to use some of these processes.

Steps

  1. Connect UART debug serial to the board.
  2. Use putty or terminal to verify that device is unable to boot due to onboard eMMC image.
  3. Prepare a microSD card for recovery (it will wipe all your data). Download rk3328-sd-friendlywrt-5.15-20220125.img and use balenaEtcher to prep the MicroSD.
  4. Make sure the board is disconnected from power but you have the UART connected and putty running. Now short the “MASK” positive and negative connectors in the board with some cables; I used the GPIO connector nearby as short-circuit source since simply joining both MASK connectors together wasn’t doing anything.
  5. While you are shorting the MASK and the board is powered off, then turn on board. It should short-circuit at boot and skip using eMMC for boot and use the SD card instead.
  6. Once the image is booted, use SSH to connect to the OS and wipe out the
/dev/mmcblk2

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