Onan 5500 watt LP question

[MTK46]

Never had this happen before.
I was running it had fridge, rear a/c, electric hot water and started the microwave. Power shut off generator still running.
I shut generator off and waited a couple of minutes before restarting it. It started but power never came back on.
Shut it down again and checked the switch panel on it.
Mine has a 30 & 20 amp switch. 30 amp was on 20 amp was off. Turned the 20 back on. Went to bed.
This morning I started the generator and all is fine.
So was it the 20 amp switch that caused the problem?
If so with the 30 one on why didn't I have some 110v power?
It couldn't have been the transfer switch as I plugged in my cord to a 15amp plug and did have power.
To tell you the truth I never paid any attention to the switches on the generator before.
As I bought my MS used and the hour meter wasn't working I don't know how many total hours are on it.
I changed it out right away and in two years I've put 65 hours on it. I don't think it had a lot on it when I bought it.

So any ideas?