Ducadim,
There are many signs of flash chip damage:
1) update.log shows UnitID=0. That means region 0x22 was erased. Normally, It doesn't get erased accidentally.
2) xrgn,41 failed.
3) "NO IMAGE FOUND" instead of images. That means region 0x7F was erased. Normally, It doesn't get erased accidentally.
4) You can't flash firmware in pre-boot mode
So, personally, I think your unit is very very sick, and it can't be repaired using purely software methods.