hi guys first post here looking forward to hopefully a helpful community lol
soooo car entered limp mode and ran like shit had it towed home
tow truck driver started it up once home and it died
i got in it pulled it in the garage still in limp .... cleared what seemed like every code possible out of it
started car back up to no cel .... the moment i put it in reverse light kicked on car ran like crap again
went to pull codes again had nothing shut car off ..... and that was it ....its dead guys D.E.A.D.

after trying to start again ... came to these codes
2b21 throttle valve actuator pre drive check 1
5e19 dsc can dde torque reduction not possible
a0b4 car access system engine start starter operation
d2c4 ca k-can line fault

few things to point out after disconnecting battery to start going through some stuff i found online only a0b4 and dc24 have returned .... pulled intake off and disconnected plugs to lift harness to get to the starter ..... i have 12v at power cable to starter.... however .... there is corrosion from on both ends of starter cable and where it meets alternator as well as the ground strap is green with corrosion ... but all seems to be intact

im new to bmw so please be as long winded with your explanation as possible still learning the cars and terminology
where would you start ...
i feel like the throttle valve actuator is my problem for the limp running but will that cause the car not to start
what are the odds that the starter went at the same time i know its a common issue for these cars but im just at a loss
and then this whole k can line fault ...are there common places that the wires break and if so where

thanks guys