It's very hard to remove the glass when it is shattered in multiple places around the edges. Once you get going it comes free easily enough until you hit another crack. Each crack is an effort to get under. During this process I managed to push crushed glass into the lcd and crumbled the edge. Unit functions fine but shows a small light leak on one corner.
If the screen is shattered around the edges you are going to need to reheat the warmer regularly. Best to set up near a microwave.