Here this one seems more up your alley: https://www.bimmerforums.com/forum/s...Power-on-reset

EDIT: Maybe get a jump pack or trickle charger, charge it for a while and then try cranking once you clear the codes. They write in the forum post for that persons situation, “if a battery is aging.” Which if yours was at 11.6v makes me suspicious of it generally speaking. Coming from electronics, devices like phones will throttle themselves near the end of a battery lifespan because consistent high voltage is no longer possible from the battery. Granted those are lithium and we’re with lead acid (I think that’s all true lol, I’m not sure)