inverter in rv

I am hoping I can get some guidance here because I have very little experience with 12 volt electrical. I purchased a used truck camper that was set up with GoPower solar and 2 6v deep-cycle batteries. It also has a converter (battery charger) and a GoPower 1000w modified sine wave inverter that is hardwired to the batteries. The inverter worked fine when I got it, but the first time I used it, had it plugged in to power the shore plug and the refrigerator was on while we were driving. When I stopped to get some groceries, I heard a beeping in the camper and found the inverter was the cause. I switched it off and then back in and it seemed to work fine. I could find no cause for the alarm. I continued to my destination. Upon arrival, the inverter appeared to be OFF, but the switch was on, display was blacked out. I switched it off and on and it did nothing. The batteries were at full power (100%) and I camped on them for 4 days without any problem, using propane for the 'fridge. The lights, pumps, stereo and 12v appliances all worked fine. FWIW, the fridge draws 350 watts when on 110v power. So, I pulled out the inverter to see if I could find a reset switch. There was none. I figured maybe I had blown a fuse on the inverter, so I checked all 3 fuses. All were fine. I checked the power from the battery and it was 13.6v (well within the normal range) and that meant the slow-blow fuse between the batteries and inverter was okay. The wires from the battery are about 2' long and they are very heavy gauge wires with heavy connectors.. all are GoPower and were the size sold with the solar/inverter package. So, I checked all connections and hooked up the inverter again and it still wouldn't work. But, I noticed when I switched the power on, the green "on" light and LED display would flash very, very quickly and there was a slight click sound inside the inverter. I was unsure if it was doing that previously, it may have, but I maybe wasn't watching closely enough to catch it. So, I got another inverter, figuring this one was fried or something. I picked up a Whistler 1200w modified sine wave inverter and hooked it up. It did the same thing. A quick flash of the display, coupled with a slight click inside and nothing. I have tried putting max load on the batteries and test it and the voltage does not seem to drop, so it is not the depth of the batteries. The wiring is solid, heavy gauge and short. I am stumped.   Any advice would be greatly appreciated.

Interesting. I wonder if the fridge's 12V input has partially shorted, though a 1kW & 1.2kW output inverter (RMS) should have reasonable overhead (slack) for partial shorted heater turns. Maybe measure the resistance of the fridge's heater (input). Assuming 350W that should be R = VV/P = 12100/350 = ~35 Ohm but it may be as high as 50 - 60 Ohm when cold (cold resistance). It should however not be less than ~30 - 35R. If those inverter Wattage ratings are peak, then presumably the RMS is half their rating so there'd be less tolerance. (Here inverters are rated for steady-state RMS; to have other "Wattage" ratings are in lieu is illegal and useless.) For compressor fridges I'd warn that some inverters need to be sized up to 3x the motor rating, but that's not relevant for 2- or 3-way (absorption) fridges, though the heater may have a high inrush current (ie, based on its heater's cold resistance). The original beeping I could imagine being from low voltage because the engine was off. 350W @ 12V is about 30A which is a big load depending on the battery capacity. The voltage at the inverter 12V input terminals should be measured when not charging with the fridge operating - preferably after NOT having used the 110V input to ensure the max current with its cold-resistance heater. (Maybe the gas also heats the electrical heater.) It might be an intermittent supply failure (bad connections etc) that has blown the inverter electronics. (Or even intermittent output or fridge loading - especially if a highly inductive heater element = high spike voltages.) The inverter will take higher current at lower input voltages, but that's in part what its low-voltage cut-out is for, and it should also have thermal protection. But that's where I'd suspect a low resistance heater element etc. FYI - I once dreamed of a 2- or 3-way fridge. But then I realised how much electrical power they required! So I lashed out on a 12V mobile fridge (specifically and Engel 40L) with its maximum 2.5A input but usually never more than ~1.5A and that's at low duty cycles. Hence no 30A load on my alternator etc and a fridge that is easy to run off solar, and is independent of gas.   

This may have been mentioned in the Theseus above, but if not, you need to check the input voltage during this power up and make the display flash episode. If there is no current draw, there will be 0 voltage drop.