did you measure the battery voltage with a meter before you replaced them?
i would check for two things:
- do you have a battery disconnect switch and is it set so that the batteries are disconnected?
- check for a small 12 volt resetable circuit breaker in the 12 volt battery cable. it should be very close to the batteries. there are different styles. try to reset it.
use a meter to check voltage at each connection in the battery cables from the battery out until you find where the voltage stops.
2015 cardinal model 3825fl
2015 dodge ram 3500 dually