So when the cartridge is in the printer, on powerup after 2 seconds you get the error lights. Yet without the cartridge out the printer initializes and asks to insert toner cartridge. When you insert the cartridge at that time it errors out again correct?
First thing I would have to try is a different cartridge. I have never heard of this problem so I can't recomend any other part. IF I had a main drive laying around I would try that too.