code p3102 and intermittent triangle of DOOM

alright, I went ahead and bought a new 12 volt battery after testing the car by jumping it off a good battery. The codes cleared like they always do when you disconnect the battery, but none came back except for the AC codes (B1421 sun sensor and B1442 air inlet damper control servomotor). only weird thing was when I tried to start it it lit up all the warning lights except for the triangle and wouldn't move. I plugged in the code checker and weirdly there were no new codes. Restarted the car and it worked fine this time. No clue what that was but I'm hopeful it's fixed!