Thorfire stands behind their products, they will take care of you. Contact them directly.
They have sent me replacements on a flashlight and a defective battery and charger in the past. They really do want you to be a happy customer.
That being said, have you troubleshot the tail switch yet?
If you have a Volt Ohm meter you can check to see if the switch is working by doing resistance check.
Or, First thing to try is using a piece of wire or paperclip and short the end of the battery to the flashlight tube, if the flashlight lights up you know it is the switch.
If that makes no difference then pull the driver and push the lens and reflector out and check for voltage at the LED.
I would try loosening and then re tightening the driver ring and the tailcap ring before tearing it down, could very well be bad connection.
Looks like the driver is 17mm according to some comments on the previous version here:
Lot’s of good info in that thread.
Also if you want an OP reflector consider making your own with clear spray paint.
Old Lumens (RIP) had a thread about doing them that way.
Found it, here ya go;
Hope this gets you somewhere.
Later,
Keith