Looks like others have given you all the info you need to get that generator started but again,if the house batteries (if in fact you have two like we have in the 2860) are bad obviously no amount of charging is going to help
Get them checked out and replace them both even if only one is bad
As was mentioned on other posts my 2014 was purchased in July '14
I put new batteries in last month (13 months)
Everyone is talking about "what may be pulling your batteries down"
I think you possibly have junk batteries that may need replaced.
If you are parked unplugged with the master battery switch off good batteries don't just drain
I never saw a Hearse towing a Trailer
'71 Dads VW camper pop up Van
'93 Coleman pop ups (I'm Dad)
'04 Fleetwood Jamboree 26q
'14 Sunseeker 2860DS