Just spitballing here -
-Any way to revert your ECU to your original tune (before your bud did his coding)? Worth trying to cross one thing off the list imo, but could be tricky if you don't have a batt charger
-My center console light usually stays on after I lock the car because the plastic tab on the bottom of the door broke off, so it thinks it's open all the time. Could be a draw there
-Where'd you measure the 14.2v at? Under the hood, from ECU, on the battery itself? Did it fluctuate at all? If that's at the battery and not swinging wildly, I'd imagine alternator/voltage regulator + circuit to batt are ok
-Can try pulling fuses and checking draw, a la these guides
here and
here
GL and let us know what you find. Been frustrated by similar issues in the past too, shit happens but don't let it get you down! Good times ahead