Heart inverter, link monitor problem or maybe battery

[cdat]

Went to Portland Or last week, great trip, coach ran great going and coming back, over the Blues, up and down cabbage hill, no problem, no overheating.
After parking in an RV park, we went to visit our daughter, came back later that evening, noticed the inverter was extremely hot, the link 2000 was flashing "low bat" in the left corner and there was an "E" in the right side, not flashing just steady. Would not allow me to make changes to the Link, finally turned off the inverter as I was scared it was going to catch fire it was so hot. Apparently the grounds crew was spraying bark around and had partially disconnected our power supply. The next morning I changed to a different box, and turned the inverter back on. It did not overheat, but the link kept flashing low bat along with the steady E. Did the same thing all the way thru the trip regardless of the park we were at.
Yes, I do need to check the batteries, I know they have fluid in them, but not sure if they are any good. How do I test the inverter and link to make sure it's not causing a problem before I put new batteries in if the batteries are in fact bad?
I did check the manual for the link, shows various codes for problems, but nothing for a solid "E". Any help or ideas on where to start would be appreciated as I'm not particularly competent when it comes to electronics.

thanks
John