If you have to ask the question, my advice to you, after years of repairing cellphones, is please don't try to repair a cellphone ever again. You can to out and buy a T4 bit (you should have a complete set anyway), but if you run into problems, see if there's a shop that will take what you worked on and put it back together again. (I doubt that you'll find one, meaning that the phone is now a paper weight, but you can try.) In the future, you'll find it's easier to have the phone repaired than to have to buy a new one.
By the way, leaving the power plugged all night won't fry the battery - the charger (that's part of what's inside the phone - the thing you plug in just supplies 5 Volts) shuts off the charge at about 100% and start it again at about 98% if the phone is on and the battery drops a bit. You waste electricity that way, and generate a bit of heat on the motherboard, but it doesn't fry the battery. You probably had something running that was using more than the charging current, so the battery slowly discharged overnight. All you had to do was turn the phone off and charge it.