I used a heat gun, plus a digital thermometer (auto type). Heated it to 75C. Had to do it multiple times.
Here is the trick.
1/ Do not put the suction cup on until you are finished heating, otherwise when pulling the pull point is too hot and soft.
2/ Mine was a Nokia 7 plus, metal back, but regardless, heat both sides. If just heating the one side you are only heating one side with glue, you want to warm up both sides, and warming both sides will keep it warmer longer while you work.
3/ I used the metal pry tool, it worked if I used the suction on the glass, and the pry tool at the point I wanted to get in, so was pulling with the suction and pushing the opposite side with the tool, if both sides heated 75C, it will let go, otherwise trying to jam the tool in you will be doing it forever.
4/ Once you get your tool in, only go as far as needed to break the glue, that is about 1/6”, max 1/8”. The videos I watched for my phone did not indicate this, so when I put my phone back together, the phone turned on no problem, but I had somehow broken the screen connection with the tool going in too far.