customers truck im working on here, its a 2021 ram 3500 cummins , its got a bad / missing ecm. he semt it off for repair and hasnt seen it since. they said it wasnt fixable and then didnt send it back/ sounds fishy, hes wanting me to get it going for him. he doesnt want to spend the 3800 $$ for a new ecm. found a used on with the same pt # same transmission. hows the best way to reprogram vin and security keys?