BBB eMMC failure


We have a BBB returned from the field after just 3 months of operation. It runs kernel 3.8.13, and console shows the “C” letter when booting from eMMC, indicating that there is no valid boot.
Booting from an external SD Card with the latest debian image available works, but it shows this message:
mmc1: error -110 whilst initialising MMC card

Obviously, mmc1 does not appear on the /dev list, so we cannot use the mmc-utils tool to read the eMMC

We have measured the supply voltages:

  • VDD_3V3A - 3.3V
  • VDD_3V3B - 3.4V

We are pretty confident about the surrounding hardware and software, as there are around 2k devices on the field, summing more than 12 millions hours of operations with no failure.

Any idea on how to proceed to find out the failure root cause?