If you have this green laser you might think it is impossible to open it up but when i had nothing to loose i tried everything.
First you need a pick like the one that i have to remove the rubber foam from around the battery spring.
The circut board can be pressed down far enough to get the on/off button out of the tube. After that you need to try to get as deep into the laser as possible and get the whole circuit board to twist out of the frame.
MAKE SURE YOU APPLY EVEN PRESSURE TO NOT BREAK ANY OF THE CONNECTIONS.
YES I DID BREAK OFF THE ON OFF SWITCH FROM THE CIRCUIT BOARD BUT THIS WAS A LEARNING EXPEREMENT SO.....
gently twist the circuit board lots of times. it is a fine thread so it moves out very slow. you might have to twist 20 times to release it.
I WOULD ONLY TRY THIS ON A CHEAP LASER.
WATCH MY OTHER VIDEO ABOUT HOW TO JUST REMOVE THE SILVER HEAD! YES IT CAN BE DONE WITHOUT A PIPE CUTTER!!!!!!!