There is a couple of things I would suggest looking into. First just make sure the LED strip still works, then try a adding a current limiting resistor to the strip, even if it already has one it could help. A unity gain buffer could help as well. I also noticed that there is no active regulator on it, and all the work is put on a zener so I would also say either jank in an active regulator or even easier, supply it with a regulated rail