MTD do_write_oneword fails

You are correct about the part where the sectors need to be erased - this is done by the MTD.

The MTD reads the sector involved (places this in a RAM buffer), erases the correct sector, places

the new file values in the RAM buffer and then commits this to the erased sector.

If it was a problem with the Flash not being erased before writing, then the failure would not be random,

but rather it would fail at the same addresses each time, as they were not erased.

I'll try to see if I can narrow down the problem by enabling the MTD debug.