2000 Dodge Durango Craziness ensued.

I have 2000 Durango SLT 4.7 V8. I am selling it so I decided to change the oil and fix the leaking pressure line to the power steering pump so that I felt good about the deal. Everything went great. Then I went to start the vehicle, It went to turn over, then stopped. A ticking noise was coming from the glove box. SO I jumped it, and after a few long tries it started. As soon as I shut it of ten minutes later or so, it died again. I then jumped it again and now noticed that there was a high pitched squeal coming from what sounds like the gas tank. Its not really a squal but just a high pitched sound, like a constant ringing in your ear. So I took it to the auto parts store and they said that the alternator was bad. I bought a new one and installed it. The same thing happened again. By the way there was a harness that connected to the pressure line and Im suspecting this harness had something to do with all this all of a sudden hapening. Everyone says that its very possible that all this jus "happened". I dont buy it. Thaere has got to be something much larger going on here. I havent had anyproblems with this truck except for a slow leak in the pressure line. Please help

Anthony LaMarca