I've been experiencing the same issue for the past month, and I'll tell you what I've already done to maybe save you some trouble.
From what I read online, I thought my sync module was the culprit. I ordered a new one (found one on eBay for $120), and it seemed to temporarily solve the problem. About a week after I installed it, same thing was happening.
I did some more research online and found that maybe there was excess flux from soldering the board on the back of the radio. Seemed like a stretch, but I disassembled the entire thing, cleaned it with 99% isopropyl alcohol, and reinstalled it. No luck.
Eventually, the radio just went dead completely. No audio, no buttons working, just the time flashing.
I ordered the Navos unit from American Muscle and just got it installed today. Definitely worth the $900 - driving with headphones in is such a burden.
Sorry for the bad news pal.