If you have no power, either the batteries are not connected properly, the battery disconnect switch is off, or there is a huge circuit breaker somewhere that got tripped.
Most Thor units use a disconnect switch actuated with a solenoid. You may simply have to turn it on.
If you have 4 batteries they should be hooked up in series/parallel if they are 6V batteries, or all in parallel if they are 12V batteries.
For 6v batteries, they will have two sets of batteries in series (6V + 6V) and both of these sets will be in parallel.
For 12V batteries, the only choice is to connect them in parallel to maintain 12V.
This of course assumes you have a 12V system.
The only thing that works on a RV is the owner...