I removed each battery cable so I could clean the terminals. First, I disconnected (-), cleaned it up and put it back on. Next, I disconnected red (+), cleaned it up and put it back on. There was quite a bit of corrosion product on the terminal, so I cleaned the end of cable with hot water and baking soda. While doing this I protected the top of the battery with a towel and no baking soda/water came in contact with the battery. I rinsed the (+) cable with water and dried it thoroughly. Again, no water came in contact with the battery. The truck won't start. It won't crank, it just clicks. I checked the battery voltage and it was at 12.4. Any ideas? It was fine before and mostly started easily with a single turn of the key.