I have a similiar problem, but I did not have the pleasure of replacing my battery and starter. I just drove thru some high water. (I know, not supposed to do that) The next day the unit acted like it was not getting power. I removed the unit and had it checked at an authorized sony repair shop and they said it was working perfectly, so it must be the wiring. I re-installed the unit and have skinned the insulation on the wires going to the radio connecting plug and voltage measures 13 volts. Still the unit doesn't turn on, So I am stumped.
Have you heard anything?