While "free" schematics are often hidden behind paywalls or forum registrations, you can try these specific avenues:
Version 1.3 boards are often lead-free; check for brittle or cracked solder around high-heat components like inductors. bm5291 ver 13 schematic free
Usually designed for DC-DC conversion, featuring high-capacity electrolytic capacitors for filtering. While "free" schematics are often hidden behind paywalls
Use a diode test on your multimeter to check for shorts between the Drain and Source pins. bm5291 ver 13 schematic free
Use a multimeter in continuity mode to find the common ground. This is your reference point for all voltage checks.