Just dead… After nothing… 
I have other for parts, and hotair for removal part by part.
Which chip replace to have bootloader working? RS-232 show nothing because RB not booting!
https://www.dropbox.com/s/rvfmwmsn8p9rc3k/2013-05-17%2009.59.43.mov
Have you tried to load secondary bootloader?
You’ll need also restore license key, because SW ID and MAC stored in BOOT. If you replace BOOT and NAND from another board then license will also remain.
No response 4 all procedures described here 
Without problem i`ll
replace all the chips - show me these chips please…
U502 (NAND) and U503 (BOOT).
Thanks, i will try 