Or use an old toothbrush with baking soda solution.
If after getting it "clean" and you are able to get the accessories to go on, check to see if the alternator light is on when you have the key to on without the engine running to confirm if the alternator bulb is still functional. At 100k plus miles, you've had a good run on the alternator. You might have a problem with the alternator without knowing it if the alternator light is blown. But try all cheaper fixes first. The dealer charges something like $600 to change the alternator. Unless you change it yourself.
