why my apple tv1 is flashing

First, stop being impatient.

Second, basic forum etiquette, SEARCH before posting.

At the very least, check the "More Like This" Section over there =========>

Welcome to the Apple Community.

It may be that your device has failed. I'd suggest disconnecting all the cables for a while and trying again in a while, if the problem re-occurs there may be nothing you can do.