Electrical issues?

Discharged battery. If you leave the battery connected and park it for more than a week, your battery will be dead from the parasitic draws of the alarms, circuit boards in standby, or volatile memory devices. If this is done more than a few times, you'll be shopping for a new battery. A battery disconnect switch is the most convenient solution for this.

Dead battery. How long was it without power? The battery must be either disconnected or kept on a charger/maintainer.

I agree. Microwave is a 120 volt side of life device
Everything else you describe as not working properly is teh 12 volt side

Shorted cell in battery would be my suspiscion #1.. Converter issues #2

Step one: In battery compartment mark all wires hooked to the POSITIVE terminal with red paint or tape, remove and tie them all together, insulate (Plastic wrap is good for this)

Mark all NEGATIVE terminal wires with BLACK remove, insulation optional.

Remove battery or batteries to bench for external charging with a quality 3-stage smart charger

Remove to automotive store for quality testing.

IF You find you need to replace.

A GC-2 Six Volt Golf Car battery fits in the tray for a Group 24, only it is taller so you will need to make some changes (Longer bolts on the hold down clamps may be needed)

You wire them up like this

Negative side {6 Volt Battery} +Jumper- {6 Volt battery} Positive 12 volts.

They do drink Distilled water from time to time but they reward your effort with LONG LIFE.

Did you take the battery out for the winter? Sounds like you are having a battery or a converter issue.

What do you mean "turned the power back on"?

And which light for the microwave---do you mean something on the microwave itself?

Your lighting system runs off 12V and the microwave is on 120.... if it's just things on the 12V system, my first guess is a dead battery.

Please give a clearer description of what you did and what happened, so people can help you.