I believe the battery units contains the fuses so I would start by cleaning the contacts on light itself. There is a good chance there is some corrosion on them. If that doesn't work , call your local Pelican Centre and talk to them before you disassemble the unit. Pelican has a good warranty and they have always stood behind it but the PAL lights only have a warranty of 1 year. There is a good chance they will cover it anyways or at least provide some tech support.
If that fails then I would suggest you remove the light head and check the wiring connections at the top of the mast. If it looks good then check the bottom connections near the mast. Check both ends of the wire that runs inside the mast for continuity. The mast should be the only moving part so its likely the failure is there or close to it. To be fair I have never actually disassembled on of these units so I do not know what tools are required or the procedure to do it.
If you do take the unit apart would you mind posting pictures?
