92' civic code bad ecu help

Trying to help my brother his civic (stock) . car stalled out and would not restart. He has fuel and spark and he pulled the valve cover to ck for a striped timming belt the timing belt is turning the cam. (hope it has not jumped) He pulled a code and it said the ecm was faulty (code 0 ).
any ideas for checking the ecm. thanks for the help.

I will do a search for the code 0 as well.

Did not find any help with the search need some help if you can
thanks

swap the ecu with a known working one.