Step 2: Open 'er up
Start by removing the battery cover and batteries as there are two screws hiding under the batteries.
Flip the unit over and remove the other two long screws. You can leave the belt clip intact. The two short screws can be left in even though I didn't. They hold the switch in position and removing them will only mean that you will need to line it up again later. Learn from my mistakes and leave them in.
There, four screws out (plus one for the battery cover) and you should be able to look inside.
Kind of exciting eh.