A flashing light is trying to tell you something. Get the manual out, look up "calibrating throttle range on ESC", it should be one of the very first things you have to do.
The purpose of this is to let the ESC learn the throttle range of your transmitter, and is very important to do. Be sure to center all trims on the radio first! Find the instructions in the manual and perform the cal procedure. Once done, and you turn off the ESC and turn it back on again, the only light the ESC should give you is when you give it throttle. If after doing the cal, you still get a flashing light, then something is wrong, probably with the ESC.
Is this a brand new car? Brand new electronics? Or did you supply your own? Maybe a problem with the receiver? Make sure the steering servo is plugged into receiver Ch.1 and ESC/throttle is plugged into Ch.2. You also might try UN-plugging the servo, see if you then get throttle. If you do, then the servo is bad, and "browning-out" the ESC.
Last edited by EXT2Rob; 09-08-2014 at 08:19 AM.