Stuck on Target Disk Mode due to Firmware Password

The MacBook Pro 2014 (macOS High Sierra, A1502) I’m using has a firmware password set. I tried to boot into target disk mode and it asks for this password even after turning it off/on. I tried many key combinations, SMC reset, cmdoptionPR, etc, none of which worked. I just want to boot from the main drive again so it works as usual. Is there anything I can do apart from waiting until Monday to resolve it at my school? I need this thing for the weekend.