Nevermind, I figured out the problem, and if anyone else is having this issue it's because your batteries are just *slightly* too short and aren't contacting properly. I had some slightly longer 18650's and those worked just fine .didn't really know where else to post this so here goes - I just bought and received a Sanwu Challenger II 3W 445nm laser in Single Mode operation with one 18650 battery for power - and I have not been able to get it to turn on for more than a brief second. Is there a method to unlock it that differs from the instructions on the site?
I did search around here a bit and saw someone having similar issues but that was with multi-mode operation.
I have tried single half presses, which prompts the beam to appear for a second-ish as is what happens when I power it on, and the same with 3 half presses and 5 half presses, or really any number of them.