Car only starts when jumped, quits when brake pedal is pressed

I drive a 1993 Mazda 323 hatchback. The battery light on my dash board turned on one day. Because I drive an old car, I've gotten into the habit of not worring too much when the warning lights turn on, especially since my break warning light turned on not long after I had the breaks replaced. About a month after the battery/charge light had turned on, my car cut out on me in traffic. My brother had to jump it and add water to my battery. He came over later and we used a voltmeter (I think that is what is is called) to check the electrical system. After hours of fuses, plugs, lights, and whatever else he checked, he unhooked a small black and white box (it was only about 1/2 inch in size, I can't remember if it was some sort of fuse) from underneath the steering column and the meter stablized at 14. We thought the issue was solved, but the battery still died that night. So I replaced the battery the very next day. The car started fine after that. Just to be on the safe side, I kept the battery terminal disconnected at night when I wasn't driving. The car ran fine for a few days. The only thing I worried about was the fact that the battery/charge light on my dash was still on, except when I engaged my breaks. Only for those breif moments with my foot on the break would the warning light turn off. Not four days after replacing the battery, I came out of the store and tried to start the car. There was some little charge, but after trying three or four times trying to get the engine to turn over, the small charge was completely gone. I had someone jump the car and I got about 1/2 mile toward home when the engine slowly began to die. I figured that at this point it was the altenator. I began to pull off the road, and when I touched the break the engine suddenly quit, like I had turned the ignition off. After having the car towed home, my brother and I took my altenator to be tested at Checkers. It failed and we purchased a refurbashed altenator (I was told most altenators now are usually referbished). After installing the new altenator, the car still wouldn't start. There is no noise when the key is turned. We tried jumping the car. It started. But when I put my foot on the break to move from park to reverse, the engine suddenly died. Again it was just like when the ingnition is turned off. We jumped it twice more and each time when I touched the break the engine suddenly died. I'm ready to pull my hair out! Is there anything else my brother and I can try to fix it?