I have had a similar issue. Check for 12DC power at the terminals of the inverter. There is likely a large Buss-type fuse between the battery bank and the inverter.
My inverter failed in such a way that there was an intermittent internal short in the inverter, and the fuse would blow when the short occurred.
The fuse on mine is bolted in its holder to the wall of the battery compartment. Fuse on mine is this one:
The bad news is that this was a costly repair, enough to make me consider just replacing the entire unit.