2001 330Ci problems

I have a few problems with my BMW that i would like to get fixed without having to drive very far to a dealer to get them fixed.

first, my temp gauge says it's -40 outside
second, my trunck sensor says that my trunk is open
and third, i can not put the top down, im thinking it's because the trunk lid sensor, not sure though

can anyone please help me, im trying to sell the car and dont want to pass off a lemon to someone else.

thank you