Astrolux MF02 Stopped Working

I have a Astrolux MF02 XHP35 that I purchased May 2018. It is in near flawless condition and has never been dropped. I keep the light partially unscrewed as to not drain the batteries with the side button light.

A few weeks ago it was working fine and I just noticed it will no longer turn on. The green side switch also will not light up. I checked all the batteries (4) and tried another set with no luck. The battery carrier does read a voltage of 8.0+ volts, I believe it’s a 2s2p setup.

For the heck of it I also used my volt meter to test the spring and retaining ring on the head only and it read a voltage, but slowly decreasing. Does this mean power is getting to the head via the battery carrier but something is wrong inside? I tried tightening all screws on the carrier but since it’s displaying a voltage reading I don’t think that’s the issue.

Is the tube tightly screwed too on the forward side?

Sometimes the ground contact either in the forward or front and/or rear side of the tube is lost due to grease, dirt and should be wiped clean and dry.

Yes I tried making sure both ends were extremely tight. The spring still feels like it has good compression so I’m not sure what’s wrong. Should I try and use wires to directly connect from the battery carrier?

Anyone else have any ideas? Thanks.