Looks like the component i'm guessing is smoking is https://www.digikey.com/en/products/detail/stmicroelectronics/SMBJ6.0A-TR/634878 -- a big diode intended for surge protection or something. Some of the amperage columns in the datasheet mention low values, microamps and milliamps.
This isn't really what I'm prepared to diagnose. I didn't learn a lot of electronics before going crazy. I wish I had some idea what caused it to fail.
