Just got iPad Air battery repair kit and can't get the screen off

The glue on older iPads can be dried out and it can be really strong. You need a lot of heat (80 degrees Celsius) to soften the adhesive. It can help to apply a few drops of IPA or rubbing alcohol along the sides, it wil soften the adhesive as well. Do not pry too hard, if it does not lift easily you will damage your screen. Life hack: back in the days when I did not have a heat mat I used my party grill with a flat plate on low heat. Just keep it below 100 degrees to protect the screen and plastic parts. The iOpener also works well, but the iPad’s case dissipates the heat really quick. It can help to heat the entire iPad to help the iOpener a little.