How to diagnose spark failure 2002 dodge neon?

after checking and replacing ckp and cmp and confiming coil pack function pcm continued to throw codes for both position sensors; timing cover was pulled dnd timing belt (new) installation was twice confirmed as correct. pcu was replaced with an identical unit (correct pn according to dodge) from a rear-ended neon-same codes and no spark. this neon was parked by it's prev owner after srtipping the original timing belt at 83K miles, and left sitting over 6 mo without battery power. It is also possible that the replacement pcu has not been powered in some time. So the 64K question is does the pcu now require an expensive reflash at a dodge dealer ?? PS. valve damage was dealt with by replacing the head with an identical unit.