Power issue, lights flicker, won't level, slides won't go out

[Areynolds]

we bought and brought home our 2021 Jayco pinnacle 2 weeks ago.
Today we pulled it out to start getting it ready for a trip. We plugged it into the house. First we tried the auto level and it won't start going, status goes from processing to lost connection to idle. While individually bringing the legs down the lights on the interior begin to dim. The hydronic motor will make this grinding noise at times to, almost like it too is loosing power. Of course the slides will not go out either.
Do we have something turned off that needs to be switched on!? Could our converter be bad?
We are new to the RV world and although we thought we listened well while doing the walk through we are at a loss.

[RoadrunnerII]

If you parked it for two weeks with no power the propane/ CO2 detector can pretty much kill the battery.
Leave it plugged in overnight see if it functions better.
We leave our Eagle connected year round. Keeps battery fully charged

RoadrunnerII

[Grumpy]

Sounds like a possible dead battery or loose connections at the battery. For the slides and jacks to work you need a fully charged battery, the converter just gives it a boost.

EDIT: RoadrunnerII won..

[RetiredOne]

Put a digital volt meter on the battery when the rig isn't plugged in. If it's a good battery, voltage should be over 12.6 volts. If lower, battery is bad or needs a charge. It could even be damaged. I had to replace my coach battery when brand new, because the dealer let it discharge too low.