Frostbitten Bimmer.

Troubleshoot BMW 325i headlamp switch. License plate lamp stays lit when headlamp switch is set to any position. Pulling key from ignition triggers warning indicator that headlamp switch is still in an on position.I live in region where it gets bellow freezing for days at a time. Problems with this happened shortly after a freeze. Also during this time I used pressure sprayer for road grime, freezing my door handles and passenger side seems to have broke linkage or unattached. Not sure being they are electric, a malfunction may cause some sort of warning buzzer or open circuit somewhere. I'm tired of having to go to the trunk at every start and stop to hook or unhook the battery. Could I be causing damage to the ecpu or other electrical emission parts by doing this?