Does the switch panel say “IntelliTec” on it.
If so, it may be either the BD2 or BD3 depending on if it has a battery voltage meter on it or not.
Here’s the manual - http://techsupport.pdxrvwholesale.co...ice-Manual.pdf
The one or two that I’ve seen both had red LED’s. It’s possible your brothers has a red and green. Nothing is said of different colored LED’s in the manual that I could find quickly.
But even if his has a green one instead of red, I would think the control functions pretty much the same way.
If the Chassis LED isn’t staying lit then either the Chassis Disconnect Relay (it really looks like a solenoid) isn’t latching, or the signal wire back to the control panel is disconnected, or the LED has failed (unlikely).
Those disconnect solenoids are tricky to understand. They are electrically energized or de-energized and mechanically held closed when the control panel switch is switched to on.