16 prostar electrical fault

My son left the battery charger on the truck at 40amps overnight. Its a 16 prostar with the cummins and automatic. Immediately after this, the def guage will not read properly, the dash says electrical fault, the truck starts but when you turn it off it continues to run for 10-15 seconds with the key out of the ignition before turning off. I checked all fuses and disconnected the batteries but no luck. Any ideas?

 

Thank you for the help. I scanned the body control module with no codes, the engine shows nox sensor, def level sensor, def temp sensor. Something does seem to be corrupted as none of these codes or issues were there until after overcharging.

 

Also if i clear the codes using a scanner, the def guage goes back to where it should be, but 10 seconds later all codes return and the def guage points at 6 oclock with electrical fault showing.