Your BEC is dead. Meaning the lights are on but no ones home (or rather nothing is actually happening in the ESC).

*May* be fixable if you have some background in electronics. But may also have killed other parts of the ESC.

In futures make sure you are using polarised connectors and obey the polarity (Like XT or EC connectors) and be careful when handling a live system. Especially if you have a LiPo connected.