Also check the battery control contact with the brass ring. I had a set of batteries that I used and only one worked. I rearranged the batteries and tightened fully they all were in contact, it worked fine.
I wouldn’t bother messing with the FET or getting a new one. The incorrect voltage readout indicates there’s more to the problem than just a bad FET. Get a whole new driver, or new light.
I got my BLF Q8 in the original group buy, and it has seen some use from time to time. Mostly camping and emergency light at home. I see there’s now Anduril firmware for it. Is it worth learning how to flash / getting the hardware to do it?
I picked up one of these a few weeks ago and it worked great until the most recent time I pulled it out. I don’tt see any damage but it is not powering on, even with fully charged batteries.
Okay, with no blink it either means the driver is not getting voltage or the driver is bad.
Let’s focus on the voltage. The end of the battery tube needs to contact the driver ring so make sure these contacts are clean. Then make sure you are screwing them together fully. Maybe remove the o-ring to make sure it’s not getting in the way.
Maybe try using one charged up battery.
You can feel the spring tension when screwing it together, right? The springs still have tension?
You can also try cleaning the battery ends and the driver contact ring just in case.
Check that the driver retaining screws are tight.
Also check that the driver is sitting flat like below.