These 2 videos from Matt with adventure sport are great and helped me get started. As long as you can take apart any light you want to mod down to mcpcb so you can either replace it with a new mpcpb and led or re flow the factory mcpcb with new led [same foot print] you are golden.
Sometimes when tighting down reflectors you will get a short circuit from the mcpcb to the reflector. It will get locked in a random high mode and won't go into programming.
Before junking that 17 dollar driver make sure your solder job on the mcpcb wires aren't overly big or touching...
Funny i just got done modding a lumens factory e series tear drop head with a white 2 and h17fx. Ive installed probably around 25 h17fx in different lights and drop ins, ive probably had 2 drivers fail but it was mainly from flickering.
Ive had some from new not have the first 4 low modes...
Malkoff tri tail with Prometheus boot
Mhvast 3p 18350 body
Prometheus pocket clip
Five mega z44 head
Oveready copper bezel
219c 4k with h17f drop drop in
Finally got around to building the drop in and switch for this host. 219c 90 cri 5k with h17f and extra heat sink. Body is oveready and clip/tail boot is dark sucks. Thanks Mark
Haven't bought any fenix products in a while but i do have an older tk35ue that has an excellent 5000k beam because of its mtg2 led. You should still be able to find one. The pd40 also has a mtg2 but i sold mine because i
didn't care for the interface
Even just 3-6v regular 2 cell e series would be great. All my favorite sf's are 2 cell e series but only have full out put with 2x 123 or 2x16340. Would rather run 16650, there's always something lol.