Have you tried our search function and then tried the various things that have already been suggested?? for your search, try "zgemma stuck on boot" you will find several threads already.
If, on the odd chance you have, why not explain what you have tried to cure it, what you have done to maybe have caused it, was it working before your flashes, what you see on screen, etc. etc, etc, etc. the more info you give, the more likely you are to get a helpful reply.