07 x/walmart tractor w/thermoking apu stuck on standby HELP!

I just replaced batterie on truck...my tripac heater worked for two days after but I never hear the motor on the unit actually run. It kept the truck warm as usual so I didn't think about it. Was driving in light rain and all my instruments started to go crazy giving me an error message saying no data link. Now apu won't run on any mode(heatt, ac, fan). And is stuck on standby. Any idea? I have thoroughly checkd and rechecked batteries cables and fuses on the harnesses just outside the tripac controll module. Also checked fuses in dash.