Hi KTB and welcome to the Lincoln Forums. Then there is likely a problem with the power button on the audio unit. You can try to clean the switch/contact, have someone try to repair it, or replace the unit.
You could also try using any Master Reset procedure that may be listed in your Owners Manual. Or as a last resort (I try to discourage repeated battery disconnects for most problems), disconnect the battery for about 10 minutes to see it it may reset the entire unit.
Keep in mind this may just be a case where the unit is broken and there may be no simple fix, other than replacing it.
