the pwm ic is readable, start from his datasheet and put the schematic from your pcb on paper, takes the same time like searching 2 hours for a schematic you may never find (if you didn't get it in 2 clicks, that means you gotta reverse engineer the thing, if you aren't attracted to this goooood idea, just be consumer and buy another one, like others suggested
i vote for reverse engineering, you'll learn more
changing is the last resort for lazu and stu)pid ppl, yep let's throw anything at the bin and buuuuy another