Well, there has been a lot of problems with the Titan 12T motor after a period of time, not working. You do throttle and nothing moves, the ESC is green and at throttle its blank...
Well i had the same issue, I've tried different things and found that if you put a lubricant in the motor and do throttle, it will work! (well, for the 4 motors that have the issue for me.)
Then, you put throttle trim all the way, and keep it running for about 1-2 mins, slowly adding a little bit of lubricant.
Voila! -I don't know if this will work for you, but it did for me!