what if you remove the heat sink and put it back on and the screen stays blank and the buttons light up, how would i fix that??

Check the processor. It’s possible that you accidentally pulled the processor from the socket while removing the heat sink.
Remove the heat sink again and reseat the processor. Make sure it’s properly connected and locked in the socket.
Install the heat sink and test the laptop again.
Also, if you removed memory modules, make sure they are connected correctly.