It may not be the computer but the connection to the computer.

When you first install it, it's got a good connection because of the wiggle
action you've used, but if the pin connectors are marginal, they can come
unconnected again through vibration. I had this happen and when my spare ECU
proved a cure, I thought I'd fixed it. But after another failure I put the
original back in, and IT worked. Obviously not the computer itself, then.

Solution: clean the contact pins with electronic parts cleaner and plug it
back together making sure the pins are set as deeply as possible. Worked for
me. Good luck.