I had this same issue for over a year. Hitting the faceplate worked for awhile then nothing worked. For about 6months I drove around with no radio. Finally I got sick of it and decided to either try and fix it or get a new one. I took the radio out and disassembled. With the board connected to the bottom part of the box still I put it in the oven for 10 minutes at 385 degrees. Reassembled and everything works perfectly. I guess it was probably a bad solder joint somewhere and the reflow worked.