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