What tool do I need to recover a lcd/digitizer on a series 4?

What tool do I need to recover a lcd/digitizer on a series 4?

Series 4 lcd and digitizer damaged, Found a working lcd/digitizer. I would like to simply swap cracked screen for good working screen but it is difficult to get the screen off working unit even after heating up and tried to stick plenty of tools in between screen and case of the watch.