Comment by ylynbuilds

Seconding the practice-kit thing, but for the dead DS4 specifically: before you go hunting the joint you reworked, check whether you lifted a pad or cooked a via near the stick. On those boards the stick pins sit right next to thin traces and a hot iron parked too long will pull the pad up with the pin. Easiest check is continuity from each stick pin to wherever the trace lands, and check 3.3V is present with it plugged in - if the rail is gone you probably bridged something, not broken the stick.

Other thing that got me: no-clean flux residue plus a cheap iron with a bad ground can look like a dead board when it's just leakage. Clean it with IPA and a brush and retest before desoldering anything else.