Troubleshooting steps:

If you have trouble, following steps maybe helps:

1. the tailcap be tightened;
2. battery may be faulty, try another fully charged battery;
3. battery may need charging, charge your battery and re-try;
4. clean the contact surface(bare aluminum) inside the tailcap, end of the battery tube.
5. Insert a full charged battery, connect the negative of battery and the bare end of the battery tube using a wire or other conductive tools, if not works in this step, follow the step 6; the issue at tailcap if it works. vidio here
6. Take the pill out from the light, connect it with wires and battery; if the pill works well, clean the conductive surface in the head, re-install the pill, tighten the bazel and head, try step 5; if not work, means the pill dead, contact seller for service.

This steps is suitable for Tactical version( DBS-T/CL1H-T, Night Master/XSeacher/NM400)

The Extreme mode can't be activated, here shows how the mode works.

• try tighten the pill, test again, if no helps try next step;
• add a drop of solder to the center of the PCB to make it higher.