Solved it. Unsure how since the cord wasn't necessary to use the controller( found out through testing it without, changed it ). Cleaned it out again (accidently put 2 of the pieces of the thumbstick together upside-down, which inverted the stick) and it suddenly started working but really bad drifting/deadzones. Picked it apart cleaned it out again and turned stick pieces right-side up and now it works normal again.
So not a clue what binded the L2/thumbstick