F700 may work for hours or days and then ALL sound quits. Power off, reset do not seem to help. I pulled the unit out and while the sound was working, wiggled all my wires to see if I had a loose connection. Sound never quit. Reloaded 3.x maps and firmware, no change. Sound still comes and goes.....

Only mode is the start up nag.

Any ideas or suggestions?

well if the unit sees a short on the speaker wires, the amp will shut off and go into protect mode. this can happen from a bad wire connection, a bad speaker (and yes ive had many speakers work most of the time, then quit for a short amount of time and damage) or a dammed factory harness.