Pcm problems

Replaced bad pcm in my 2oo2 dodge dakota was good for a week now the error code po 601 pcm internal fault is back again, people are telling me it might be a short some where and that I need to do a resistance test on each circut for faults, how do I do this or should a mechanic do it and if so how expensive is this problem to trouble shoot? And did I ruin the new pcm? Please help thankyou