Thank you for your answer, but right know i tryed to connect FTDI USB <-> TTL serial (to telemtry port on Pix) and when i used kermit, connect (to flash bootloader, i need to acess NSH, and since i don’t have an USB detection as normal, i need to try these method) and i see strange ‘?’ characters poping up, but no connection to NSH. I’ll tryed with Mission Planner, sucessfuly opened com port on terminal, but then no response from terminal (don’t know why). I think my Pix is plain dead, and it was by a faulty USB cable for sure. It’s the only reason. APM2.5 is working just fine, and btw APM survived so many crashes and voltage spikes than Pixhawk. It’s a shame!
Thank you Chris once more for your complete quick answer