If the device flashes briefly and then freezes up completely it is necessary to detach the internal battery for an hour. To do this, unscrew the back and then unscrew the black plastic bridge covering the strip of grey plastic tape (which resembles a ribbon cable, but isn't). Remove the tape and look for the little white plug and socket with red and black wires going in and out. Pull out the plug and leave the device for an hour before re-assembling.
