If all of the shooting mode icons are blinking repeatedly on your HD HERO Original camera, it is to indicate that you have the UPd (upside down) image capture mode setting selected.
The UPd mode should only be used when recording with the camera upside down, in order to have the recorded image automatically flipped upright. If recording with the camera upright, please be sure to go into the settings menu and select the UP image capture setting.
Please note this only pertains to the mode icons. If the entire front display is blinking you may be in One Button Mode.