2003 Dodge 2500 5.9L cummins no start

[BoostedCanyon]

Guys,
I have a buddy that has had his 2003 Dodge 2500 5.9L cummins sitting for almost 3yrs now. He has had the truck in multiple shops and has replaced the ECM PN-3963994 CM-CM846 with a used refurbished ECM. My question is does it have to be reflashed to match his VIN? do they have some sort of antitheft on them? I still have the old HP Tuners MPVI1 and I am trying to see if i can help him resolve this issue. Would I be able to resolve this issue for him by reflashing the ECM with his VIN or adjusting anything else on this ECM. This is a first for me and wanted to get you all's input. He does have multiple codes at the moment the main one being P2509 ECM/PCM Power Input signal intermittent. Have not seen the truck in person since he lives about an hr and a half away and have yet to troubleshoot truck fuses/relays, fuel pressures, battery voltages etc. Just wanted a general idea of what I am in for.
thanks in advance.

[JDSDiesel]

Subscribing for a similar question.

CAN we flash a corrected VIN into a different ECM??