110 power

Returned home from 3 week trip. I plugged in my 110 15amp home power and couple of days later my wife wanted to clean the interior so I turned on the electric water heater for her needs. A few minutes later I disconnected my 110 volt cord and started the generator and turned on both air conditioners to cool off the interior. The AC units ran for a few minutes and shut down. The generator slowed down to idle. I checked my interior breakers and all was good. I then pulled the generator out and the exterior switch was in the off position and the plate on the generator said was rated for 35 volts. I shut off the electric water heater and turned the exterior switch back on, re-started the AC units and all seemed good. I assumed that with both AC units running and with the electric water heater turned on the load shut the outside switch to the generator to off. I shut down the AC units off and turned off the generator and plugged back in my 110 outside power and now have no interior 110 power. I checked house breakers all okay changed power cords to motorhome from different outlet, rechecked motorhome breakers and they were good, even checked ground fault in bathroom plug and checked interior fuses. This morning I disconnected 110 power and removed the cover from the transfer switch box and all looked good. With the cover off the transfer switch box I reconnected 110 power and I could hear the power to the switch come on I assume a switch moved. I checked the interior power and still nothing. I closed up the transfer switch box. When I turn on my inverter I have interior power to the microwave and assuming the dedicated plugs. Whenever I plug in my exterior 110 cord I always check the microwave. I am hoping that the problem is something simple. My generator is an Onan 7500. Thanks for reading I hope you have some ideas.