Have a client who's Sony VAIO suddenly refused to allow access due to an appearance of an unknown Password.
The computer is two years old. Sony Tech Support claims not to have a clue, after spending two hours on the phone with them. Are there any "Rustam" type techs who know the Sony desktop motherboards? Or have any success rescuing them. Sony sent a new recovery disc set, but, of course, that wipes out the entire disc and starts over. He had backed up the data to his Sony VAIO laptop, but it went totally dead. I suspect lightning damage.
My experience with Sony is they are unresolvable motherboard issues. We are hoping I am wrong.

The motherboard is probably toast as you have suspected. I have replaced a few Vaio motherboards