I know the source file is here: http://toykeeper.net/torches/fsm/anduril.2019-12-17.blf-gt-mini.hex
Believe the command would be
avrdude -c usbasp -p t85 -u -Uflash:w:anduril.2019-12-17.blf-gt-mini.hex
can someone confirm before I take the plunge? Also, I from what I gathered so far, to access the board I need to remove the bezel, MCPCB, and then the driver to flash.
Thanks!!
EDIT: Flashing is complete, but now I can’t really get the boot back on, see this post.
You don’t need to remove the MCPCB to do it; just desolder the wires going to it, so they come out when you pull the driver out. But yes, bezel and reflector so you can get at the MCPCB.
Word of warning - make sure to solder “feeding” wires to the ends of the emitter wires when you go to put the driver back in, as there’s not much loose wire there. You poke the feed wires through, then pull it into place, and the ends of the original wires should be poking through. Then when it’s through, you can desolder the feed wires, and reattach the original ones to the MCPCB.
Badly worded, but basically, make the wires longer with an extension, then remove the extension once it’s through.
I believe that command is correct, but I’m not at my PC to check, sorry!
Thanks for the response. I was imagining the driver came out through the bezel end, it sounds like it comes out through the battery end. I have read it is press fit, so how does one get it out, just pull the spring? I have already broken the spring off once (and resoldered back on). Seems like removing the MCPCB would allow me to push out the driver instead of “pull it”, but if there’s a good way I would be interested to know.
Not as easy as I had hoped. This video helped to guide me in removing the driver. Removing the MCPCB was definitely key for me, as I pushed through one of the MCPCB screw holes to the driver.
Guess I could have only removed the screw, but anyway . . .
The next big challenge will be to remove the switch boot retention ring. I think I have heard this is just pressed in, haven’t found a tool yet to get under to lift it.
Still interested in verification of the programming command, although I’m pretty sure its correct, as I’m not changing any fuses.
Sorry, yep, can confirm that command will work. I’ve got some switches the other way around (-p before -c), but it’ll be fine. Run this first to confirm connectivity:
avrdude-p t85 -c usbasp -n
It was a long time ago, and I’ve since sold my GT Mini, but I was able to remove/displace the driver without fiddling with the switch ring and boot.
I pushed the driver on the side opposite the switch with a sharpened bamboo skewer. This method includes some risk, and I’ve knocked a component off of an Emisar driver with that method.
One of the wire holes is okay to push down as there’s no components directly under the hole. Can’t immediately remember which one though.
Thanks for the responses goshdogit and oweban. I did reflash the board, it has Anduril now. 
I should have been more patient, and tried goshdogit’s method with the skewer. I recall now doing something similar on one of my lights previously.
I did end up removing the boot, and I just really can’t get it back on right. Spent way to much time trying to remove the retaining ring, just haven’t found the right thing to get between the ring and the head. Even tried using a dremel on a thick paperclip to make my own flat blade screwdriver ala Jason WW, but no luck. I have the boot back on, I’m sure it’s not water tight (not really an issue for me). I tried using alcohol to lube things up, but the flange of the boot won’t really get back in that tight space between the ring and the head, at least that is how it appears. If it doesn’t fall off I’ll be ok, but if I just rub the switch from the side it pops off. 
The switch is working better for me than when I received it, but that was the case before I removed the driver.
So, if anyone has tips to reinstall the boot, please share.
While we’re on the subject of the rubber switch cover, where can I get a replacement cover? Mine fell off and Lumintop ignores my emails.
Thank you! I will do that right now.