I have 2 100 W panels on the roof connecting to the P30L controller. At the solar connection I get a reading of 20 volts. The battery side of the controller runs to the battery charger for the 2004. Adventurer, The inline fuse between the controller & the charger tests good, as do the fuses on the charger. The charger connects to two 6 volt golf cart batteries that supply the coach with 12v DC power. We have been on shore power in an RV park for a year due to the covid. I inspect the batteries and water levels every month. When the shore power is off each battery tests at 6 volts and 12 when the batteries are wired together. The coach battery monitor shows the same readings and everything that runs off the 12v still works, lights, refrigerator, etc. yet there is is no display on the P30L and testing the voltage at the battery connection on the P30L shows 0 volts. I took a portable jumpstart battery pack and connected to the battery terminals on the front of the P30L and the display came on as long as I held the wires to the controller. I have no idea what is wrong & why there is no display on the P30L.