2015 4k 21.5 8gb ram - usb device blew two ports - only boots safe mode

[winternacht]

Plugged an external DVDRW (USB only, non powered) into port 4 of this imac, system immediately went off, on reboot system attempts to boot OSX and fails. Using a boot USB, determined ports 3 and 4 are dead. Ports 1 and 2 closest to power plug function. Successfully booted OSX to safe mode. Rebooted, same freeze on boot.

I am comfortable with some microsoldering. Is there a way I can get this mac to either function with all 4 ports, or cut ports 3-4 so the system operates?

S/N C02QL2BJGG78

 

[2informaticos]

First of all, welcome to the forum!

Considering 820-00034 schematic and boardview, confirm which ports from pages 41/42 are faulty.
One of U4600/700 chips is bad.
Each one powers two USB ports; that explain you have two faulty ports.