Following exactly as the guide said, screen cracked

The repair being done was a battery replacement on a previously never opened iphone 13 pro max. I was following the repair guide for the replacement battery exactly as it instructed. First off, the provided suction cup was not nearly strong enough. I spent almost 45 minutes frighting to get a good enough suction to even get the screen to lift slightly. I tried cleaning the screen and the cup with isopropyl, using tape on the screen (even though initially it wasn't cracked). It feels as though I need to be a professional power lifter to even get the screen up a fraction of a millimeter. Secondly, as soon as I was able to lift the screen enough to get my first pick under the screen at the bottom of the phone, the second I let off a little pressure on the suction cup, my screen cracked. is this normal? is it supposed to take a metric ton of force to get through the adhesive on the screen? I've done screen replacements before back when I worked for a phone repair store, but I've never had this much trouble getting the screen off before. Was it because this is the first time the device has been opened?

(of course the first time I ever crack a screen it would be on my personal device. The only reason I tried the replacemnt myself is because I couldnt afford the professional one, and now my phone is bricked.)