I'm currently rebuilding my 3DR hexa after a nasty crash a few weeks back, and I have one ESC (3DR 20amp) that won't turn on. When plugged into the lipo, it won't beep and I can't get the motor to respond. Replacing it with another ESC fixes the problem.
I stripped back the heatshrink on the ends, and the connections to the lipo and to the motor all look good (I had suspected that the crash might have pulled a connection loose). Is there anything else I can check, or is it time to order a new ESC? Is it common for ESCs to fail somewhat regularly?