I just installed a Kenwood kmr d765bt HU, BT retro kit, BT 4180amp, BT nonpro 7.1 speakers in the front and Polk mm651 in the rear. The system sounded great. Back the bike out of the garage, covered the speakers and a BT cover for the head unit and washed it. Went to go for a ride and the HU displayed miswired. I took the fairing off to check the wiring and everything looked ok. Disconnected front speakers at the speakers and tried again, displayed protecting. I disconnected all 4 speakers at the speakers and reset HU, protecting. Disconnected all of the RCA cables at the HU and reset it, protecting. Anyone have any ideas other than replacing the HU.

 

If the HU goes into protect mode with everything disconnected except the power and ground then it's probably a bad HU. You can also unplug the harness from the HU and inspect all the connections in the back of the HU and in the plug for damage.

 

Do you have a vapor barrier over the top of the radio? Could have leaked water through the mounting adapter at the top. Blow everything out with some light compressed air. Give it a day to completely dry out. I had a non-marine Kenwood. It got water logged twice. First time said protect on screen. Second time lost all audio output. After drying out it still worked. Sony MEX70BT got wet once and the buttons along the bottom of the screen quit working.

Eta: Marine isn't waterproof.