Laptop comes on and then shuts down again

this sounds like the laptop try's to load windows then restarts. Do you see a blue screen then restarts? or just loops? loop means shutdown restart shutdown restart on it's own and keeps repeating that process without ever loading windows. if this is the case you have issues with the operating system and should be able to press f8 during next boot up, at the black screen begin tapping the f8 key this will eventually load the windows boot menu select load windows in safe mode with network support. this will load the operating system and allow you to remedy your problem. go to start > run tyoe in msconfig and press enter when the windows pops up select services and on the bottom place a check in the box that says hide Microsoft services. then click disable all make shure you put a check mark in the hide ms first or you will not be able to boot again. good luck.

faulty memory...or mainboard is overheating..

make sure cpu fan still working.

ok