Inspired by @xvci96 in this topic and relating to the general crappiness of power buttons on these watches discussed in this topic, I decided to spend more time on fixing my Lokmat X360 power button, and it worked.
As I’ve mentioned, three out of my four watches have this issue (mine are from Zeblaze, Lokmat, and Kospet, though I also have one additional working Kospet; Janus by KronosBlade is basically the Lokmat X360).
Of course I won’t take responsibility for you invalidating your warranty, but here’s what I did. I found the ribbon cable leading from the battery to the power button “circuit clicker”, loosened the screws that hold the whole assembly down, and carefully wiggled the assembly upwards a bit. That gave me enough room to use a small pin to even more CAREFULLY pull the ribbon cable with the power button on the end of it out of the slot where it sits pressing up against the physical button itself.
Then I carefully peeled off the metal/white power button “circuit clicker” sticker. I did the exact same to the back button on the same watch for comparison, and also to the power button on my nonfunctional Zeblaze (additional to power button, its cell antenna doesn’t work).
Hopefully you can see the result below - look how much better the back button is than the power button! Under the circuit clicker sticker, there was corrosion on both the Zeblaze and Lokmat just as I had expected. I cleaned it very well with alcohol and also I took a pin and carefully scraped the round area between the center contact and the outer contact - if there is anything conductive in there, it will always complete the circuit and cause reboot loops or worse. And if there is too much corrosion, the circuit won’t complete at all and you’ll get no response.
And of course if the ribbon cable or circuit clicker/sticker is out of alignment, the physical button won’t make contact.
In my mind this also explains the issue with moisture short-circuiting these power buttons - if the sticker is loose or misplaced, moisture easily gets into the actual circuit.
Again, don’t take chances if you have a working watch, but maybe, just maybe, at least one more of you will be able to fix a watch with a nonfunctional power button.