For the Nano and Spyder series lasers, if it does not work at all or seems underpowered.
Temporary fix: Sometimes the tail piece/end cap is defective. The rest of the laser is functioning fine though.
Take a small piece of aluminum foil about the size of a finger nail. Fold it in half.
Take off the end cap, lay the foil across the end of the battery and make sure
the foil is touching the threads on the inside of the laser as you put the end cap back on.
Be sure to not get too much of the foil in between the threads of the cap and laser as you screw on the cap
as it can jam up the threads and ruin the laser.If the laser works correctly, it is a defective tail piece/end cap
Email firstname.lastname@example.org for a new tail cap.