My iPhone 4 screen went black, but still working.

So I was in the car on my way to Cypress, Texas. I was using my iPhone 4 as my GPS to get to a friend's house, but the screen went black at like 60% of battery life. I thought it was because I changed the brightness too low, because I could still hear texts, notifications, etc. So I also noticed my phone was getting extremely hot, which was also out the normal. I thought because the car was super hot that was the reason, but when I came home, I put it on the charger and 60 seconds later it was on fire, but it wasn't the battery. What should I do? I was thinking about getting the screen switched at the mall, does anybody have a fix? Don't tell me to do that rest and or restore crap. It doesn't work. By the way my iPhone is Jailbroken, Unlocked, and I have too much stuff to replace it. :c