XL4016 Buck Converter Reverse Engineering & Repair

In this video I reverse engineer a constant current constant voltage (CC CV) buck converter based on an XL4016 chip from XL Semiconductor. It was a cheap module from ebay, and it wasn't working properly when I received it. I figure out (and explain) how it works, and what I think is wrong with it. In a follow up video, I will modify it and run some tests to see if we fixed it.