2008 lsv
stock kenwood HU
stock cabin kicker cabin speakers
stock kicker amp 400.4?
exile XM-9 1 pr on tower
exile ZLD
exile 800 for tower

while out the other day, noticed the sound was gone, thought my iphone had died, changed zld off aux to listen to radio on HU, no sound.

looked at HU and display says protect mode looked at iphone, still battery, plays when disconnected from zld

HU manual says that protect mode means speaker wires have crossed.

i have not been around to do much trouble shooting, but any ideas on what to look for? what would have caused this? anything?