I have yet to see that a light I build doesn’t work- reason being I have a “build deck” to test all the parts before putting it together. Most common issue so far is a reflector shorting out (the light), but so far all drivers and LEDs have survived. But I have never flashed my own driver yet… that is certainly an adventure I would like to experience soon.
Now, working on my car (ie CAN bus, flashing modules, …)… that is a different story! lots of results I didn’t anticipate