I had the same problem with that i could get it working for like 30 minutes at a time. but the only permanent way to fix that problem is get the gpu reflowed/reballed.
Actually today i was trying to repair my xbox360 with 0102... not only the GPU or CPU has a cold solder joint, I found out that the RAM chips could have cold solder joints because i just decided to reflow everything.
So before you give up try doing the heat gun trick on your RAMs.
I looked up 0102 i found that its the CPU/GPU/RAM that may have a col solder joint. What causes that would be a junction that connects the CPU/GPU/RAM would be a cold-joint and the console is not able to determine if which chipset the fault is really at.