OK, I wanted to go outside and take some beam shots.
So I charged up the Keepower protected 5200 battery I have been using with it for two days.
Also an AWT IMR and an Efest 4200 IMR
Both are high drain batteries.
So, I put the Keepower batt in, pressed the button, ramped up normally, double click and one flash and NOTHING
Button dead
Opened and closed the tail cap, same thing. Totally repeatable.
At this time, the flashlight was not warm, had not been run.
I tried the other two batteries, worked perfectly! Not the light, the battery had problem
Put it on the charge, 4.14 volts.
Put it into my MR70, which requires a high drain battery to do turbo, no problem at all, held turbo for over 5 minutes (I re-upped it of course) until the light was literally too hot to hold!
Took my other Keepower 26650, put it into the Astrolux, worked perfectly!
Cleaned the springs and the battery terminals, no change. Will run regular modes, chokes on Turbo and light has to be reset.
So did something happen to the protection circuit?
Anyone ever seen this?
Thanks
AND……
I ran that battery down a few minutes on high in the light, and……
drum roll
Now it holds Turbo!
OK, I am guessing that unprotected batteries are probably better in this light. It must be tripping the protection circuit for some reason.
Yea the FT03 will draws more amps on turbo than the MR70. Use your highest drain cells for best results.
You are trying to use a weak ass Keepower 26650 battery, which is also protected, in a flashlight that pulls 15+Amps… 
That cell is not suitable for such light and I advice you from now on, to use your real high drain unprotected 26650s. 
Thank you
I still don’t understand why it started to work again after being drained for a while, but I switched to AWT and Efest hi drain batts.