Agree with Bob on house batteries dead, due to Inverter drain on 12v. Genny needs 12v to start & keep running.
I would suggest running your coach engine, as much as 5 minutes or more to get some juice into your house batteries; hold the disconnect switch for about 60 seconds and then, without releasing the switch, start the genny. Let both run for another 5 minutes before turning off the coach engine. Let genny run to recharge the house batteries, thru the Converter.
Larry & Sue
2005 Georgie Boy Pursuit 3180DS, 31'5" Class A, 18K GVWR, 208", F53/V10, CHF, TST 507, FMCA, GoodSam