Hi all,
I have cateye volt 400 which has similar design as volt 800.I first unscrewed the li-ion battery from the light. Then unscrewed the three tiny screws present at the bottom part of the light that attaches the mounting bracket to the light.Placed the separated light module part vertically on flat surface with the lens facing upwards.I then placed a microfibre towel on the lens cover to avoid damage to lens cover and hammered it with a hammer.The hammering causes the lens cover lens and the led circuit to get pushed backward.Then I used the hole provided for micro usb port to insert the flat head screw driver and push the led module outside.I have attached photos of the disassembled parts of my cateye volt 400.