Audio Systems: 2003 FORD FOCUS BLANKRUPT RADIO, single cd player, fuse box

Question
I just purchased a 2003 Ford Focuses with the Blankrupt single CD player Stereo(Part 7642310310) have been giving me trouble. During station setting the car radio comes on and goes off in approximately 3 second intervals. None of the buttons will work on the stereo including the on/off button. When the car is shut off, it continues to go on and off even though the key has been pulled from the ignition. We have tried fuses, checked the wiring. Ford had the radio replaced because they said it was bad. After replacing with exact model, new, the same thing occurred while setting the same location, middle right side. To me it seems more like a power problem, or a switch problem. Have you heard of this problems with Focus radios. Any ideas?  

Answer
Hi there,
New one on me! It is one of those occassions where guessing at a distance is not a lot of use and it needs hands on expert attention. As you have had the radio swapped out I would normally think that it would eliminate that element and I would start looking at the car power supplies (12 volt live and 12 volt Acc), 75% of "radio problems" stem from the car side, not the head unit, so, back to Ford and take the radio out of the equation this time and look at the fuse box, wiring etc.
Good luck and let me know how it goes, Peter