Electrical problems. HELP

[Grizzlee]

Hello, new to the whole RV game. We have our first Rv 2007 Fleetwood Discovery 39’. Bought it last Fall and with the exception of bringing it home the only trip we have made is to Tractor Supply to fill propane tanks. I have had it plugged into my house all winter with no issues. Everything we needed for our front yard sleepovers has worked on 30amp. All winter ran propane furnace, lights, TV’s etc. a few weeks ago we were going to stay in the RV overnight and were very low on propane. I noticed on the controller for the gas furnace there was an option for electric heat. The RV has two zones on either gas or electric. I switched the front zone to electric heat and set the thermostat for 69 degrees turned it on and waited to see what would happen. Front ac unit came on, which I assume is also heat? I have no clue. Felt heat everything seemed fine. I did noticed there were more lights illuminated on the inverter on the right side but only signified a few circuits on the left side. Went in the house for dinner came out a few hours later to set up for sleeping out. Wasn’t very warm and heat unit wasn’t running. My wife plugged a charger for her phone on the bed frame and noticed no power. I started checking outlets etc for power with not much luck. Noticed the inverter not lit up and now nothing in that panel is illuminated. Checked the outdoor GFI on the side of my house and it was tripped. That’s wired on the old side of the house and has old school fuses not breakers. Replace a blown fuse. Still can’t reset the GFI. Plugged the extension cord into a working outlet. Still no shore power. The other only different thing than how we ran all winter off that cord and outlet was I forgot I had opened the pool and the filter was running off that same GFI outlet. Today my cousin was over and wanted to see the inside of the RV. Couldn’t open the door with the fob. Push lock it would engage push unlock nothing. I’ve never used the keys before. One key opened the deadbolt lock but the lower key would not turn. Ended up getting in thru a window. Door is open now. Ran the diesel engine for a while. 13-14 volts on main battery. 6.8 volts on auxiliary battery. No power to start generator. No house lights. I’m handy but not with electricity. Don’t know where fuses/ breakers are etc. so I’m about as clueless to how this system works as can be. I know this is a long post but I wanted to cover what is going on as best as I could. Hopefully it’s something as stupid as me and some of you veterans can help a newbie out
Thanks in advance for any help.