I have had the same thing happen when I had a bad reflow connection. I reflowed the led on myself and apparently wasn’t soldered properly. The light ran awhile then became hot and bam into moonlight it went. I could push down on the dome and back to high it go until I let off. I reflowed the led again and everything went back to normal.
Vestureofblood has a video that I used as a guide and following his method I haven’t had a problem since.