You really need known good components to pinpoint where your problem lies. There is so many possibilities that could create that exact problem that it is difficult to tell you something. Bad ESC, bad sensor harness, bad sensors, bad connections, demagnetized motor, etc.....not necessarily in that order, and I may have left out a few possible causes. I will say that the most common cause for these types of problems is user error. Not saying you did something wrong, but definitely double check and triple check all of your work with the manual to make sure.

Wish I could be more help.