knc1, Yourcat - thanks a lot for all the tips and suggestions but I think I just hit the wall.
So I applied all your suggestions but no matter what I do, I can't go beyond offset 10303. Even when I hardcoded in the script to start from offset 10300 it is able to verify only 3 first blocks and hangs. I had re-tried tens of times and can't go a single bit further.
Unfortunately BGA soldering is beyond my skills and hardware capabilities so probably it's the right time to go shopping
