hi I would open the box and examine for melts or popped components,
and give it a sniff test,
if I didn`t have 5 in my spares pile to try
also I would consider buying another always plenty on ebay,
they very rarely play up, more likely is one of the sensors it reads and controls,
damaged ecu black box can occur in a paintshop oven or welding,,
have you attempted to explain your symptoms