Any chance you can get at the wires on the sensors?
If you can, you could try jumping them to ground and watch the panel.
Also clean the terminals, as the connections are very low voltage, and must have a good connection.
Happy Glamping.Norman, 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!