Motor failure

[Akrobatik]

I replaced one of my motors after failure and now 3 out of the 4 motors don't operate. WTH is going on with this thing?

 

[Multicoptertec]

So the one you replaced works, but the other 3 don't? Sounds like a wiring problem. I don't see how 3 motors can all fail at once, and the fact that you took the bird apart and then this happened. I think you need to have a look under the hood.