PRS-500 PRS-500; UART, U-Boot experts: HELP!

[Melongasoil]

Hi there!!!

I've recently bought a faulty PRS-500 from a member of this forum; the problem was that it was stuck on "upgrading firmware". None of the usual methods could trick the reader to upgrade or reset its firmware so...

I managed to open it, without problems, i even connected it to my computer thru a serial cable UART (after soldering those that two small wires)... I tried a couple things in console mode and, lately, i got it to boot into bootstrap using U-Boot. I tried a lot of things, i even erased some memory address from the NAND just to test if it could be done (now the reader crash before the "updating firmware" message)... But the small Linux kernel that the U-Boot uses is hard to handle... I think it's undocumented and i don't know Linux very much, so it's pretty useless for me, even after doing the hard part (soldering and running the reader from hyperterminal).
I'm supposed to fix it uploading a kernel file thru serial into a memory address, boot it from there and then run something like Universal Flasher to upgrade its firmware and get the reader running again. I've only found a Prs-505 kernel and it doesn't work... when i boot the kernel, the reader just freezes.

Obelix: I know you are "behind" all the UART, console and U-Boot discoveries; would you please help me? I'm desperate and i don't know what to do now...

THANK YOU VERY MUCH... And happy new year to everybody!!!