Here's pic of the driver removed. Size is 22MM. Don't know what that red stuff all over top is (bottom pic). Need to replace with compatible driver. Light uses 18650 or 2x123. I'd settle for 18650 ONLY as 123's ain't my thing. Light also has dual electronic switches, one for power and one for modes. Anyone know what would work in this light? My first transplant. 
Switch is good. LED is good. Just no HI output. Should put out 1000 lumens. Putting out @25 lumens as it was.
Why not contact the seller? Or contact sunwAyman directly, they might have a spare board for you!
That red stuff looks intriguing
Glue ?
Red stuff is probably an attempt to quiet down any noises from the inductor.
I don’t have one of these/am not familiar with it, but I guess this light has the two buttons in the tailcap, one for power on/off and one for modes?
Are there any wires other than the red/black ones for the emitter going to the driver?
If you test the light with the tailcap off, were you seeing the same only-low light?
Is there any electronics in the tailcap?
The solder on the two 6 pin components (Q2 and U1) below the inductor look a bit suspect. I see 4 pins - 1 on bottom left of Q2 and 3 on left side of U1 that may not be properly soldered.
If you have a soldering iron with an extra fine tip I’d try touching up those solder joints and see if that fixes the problem.
Light was given to me supposedly working couple weeks prior, but we know how that can go..
Thus, I have no warranty,,and oh the HORROR stories of SWM service and email avoidances.
Wanna cheap fix. 
Yes
No
Yes
Edit: YES. but bypassed switch to no avail unless there is some majic boosted circuitry I don't understand.
Sorry, It's such a horrible picture, but actually the joints are shiny and secure and not as they appear. Wrong angle and light for pic I guess.
If I were to attempt to solder those tiny connections, I'd be in over my head. I can replace a driver, but I can't repair one.
Yes, there should be electronics in the tailcap! As far as I remember there should be a board in the tail cap..
oops, yeh my bad. But, I bypassed the switch and same situation. No HI output.
ok.. still good to know there is something down there ;)