Zero stops booting from SD

Setup:

  • I have a Radxa Zero with 2GB RAM and 8GB emmc.
  • The Zero probably has a corrupt emmc chip because of the following reproduceable behaviour:
  1. Flashing using boot-g12.py sometimes works, more often it runs into a timeout at the end of the process. However I was able to mount the emmc via USB today.
  2. When writing to the emmc via USB after some time I get buffer errors that resemble of flash drive failure.

Due to the problems with emmc I am installing to a 32GB emmc chip that sits on a radxa emmc-sd adapter in the sd slot. I will refer to this as SD.

Problem:
I was able to setup a debian system properly and did my first experiments measuring LUKS performance on USB-drives. I shut down the system and at the next day it was not starting anymore. Observation:

  • I do not see any screen via the HDMI output.
  • The USB-ethernet adapter has no link to the switch anymore neither does it connect to wifi.
    Both was working the day before.

The Zero does not seem to be just broken as I was able to write an image (partially, due to errors) on the emmc. The zero booted from that image and provided me a responsive system I could interact with via USB and HDMI.

Afterwards I erased the emmc storage and also reflashed the uboot-sd image in the first sectors of my sd-card emmc. Still, the systems plays dead when trying to boot from SD. The SD works when I connect to another system

What can make the Zero stop booting from SD from one day to another?

Okay, I might have tried that earlier:
I flashed a fresh system on another card - and the Zero boots.

So the problem is with the original card/emmc-chip I used. Wondering why it stopped booting.