OK folks...I have a 40ft Desiel Motorhome (Alpine Coach) Unit sat for two weeks -- came back -- started unit, fine. All Electrical items on Coach fine - everything worked like a charm. Star...
If you are safe working around 240 VAC, open the ATS and unplugged, generator off and inverter off, check the connections, particularly those going OUT from ATS to main breaker box.
Since both generator and shore power are now inoperative, it suggests a problem on the OUT side of the ATS, main breaker box, etc.
This assumes when you say nothing works, that no 120 VAC items work, not just outlets.