You would be much better off with a much smaller motor. A 1515 with a kv around 1600 will be much better for 6s lipo.
The 1527 you have is capable of overdrawing the esc and batts on 6s lipo.
You gearing is a bit high for the motor rpms you ran. So I will say that it was just too much for the esc to handle... I can imagine it was very powerful.
Best thing to do with the motor is send it to neu and let them check it out for you. I would also suggest you swap to a smaller motor, like the MMM with 2200kv motor and run it on 4-5s lipo.