camera flash flashing but phone will not start

My phone was working fine today. I went out and when I got back the screen was blank and the camera flash was flashing away like crazy.

I pulled the battery, flash and sim and waited a while and when I turned put the battery back in it still kept flashing. I have tried another battery which is working fine in a separate phone, and my battery works in that phone.

I have tried the 3 button reset and nothing happens at all except the flash keeps flashing.

I have tried connecting to my PC and it sounds like the usb connection is going up and down, endless beeping.

Is there anything else I can try before having to take it to the repair shop?