Solar prewire?

colt, thanks again but that link is broken...i think it was this

to wind this up, the connector on the roof just needed a good clean with electronics cleaning spray, and some...yes...dielectric grease.

Two batteries in parallel is still one battery, electrically.

Dielectric means no electrical connection. You don't want that.

If disconnecting and reconnecting a panel restarts the controller you probably have a defective controller. You'll need to do some deliberate, logical troubleshooting with a volt meter to be sure.

The wiring from the roof to the controller is independent of the batteries and has no bearing on the number or voltage of the battery bank. It only supplies power to the controller. Then, the controller controlled the charging of the battery bank with the available power from the panel array.

You can resize pics when you upload them.

Your tech is right, you should just be using battery A terminals. The B terminals are for charging an independent battery bank, say if you wanted to charge your vehicle start battery separately. You aren't doing that so your two batteries should be connected in parallel (they are) and then connected to the battery A terminals.

I did notice one thing when I looked at your charge controller manual. It states that you should not connect the solar negative terminal to chassis ground. Both wires from your solar modules should be connected directly to the controller and only to the controller. Perhaps this is because the controller is switching the negative side of the solar array to regulate the charge voltage. In any case check to be sure that it's wired as specified. Also check the battery type that is selected on the controller matches what you actually have on the trailer.

If none of that works then to go farther you'll need that multimeter to confirm the battery to controller and solar array to controller wiring is correct.

Thanks