Screen cracking upon replacement...multiple times!

Check for frame damage, which often happens after a severe enough drop. Most drops don’t result in that, but you need to check if you dropped it and are now replacing the screen. It sounds like you missed some frame damage.

The problem with a bent frame like this is unless you have the right tools, it’s difficult to fix. If you can find a compatible gTool those work, but you can usually get away with beating on the frame if you’re careful and don’t mind a scarred final finish. I would take it to a pro if you don’t feel comfortable since you only really get one chance. That said, Apple no longer puts device specific information on the back, so you can buy a new rear housing if you’d rather not deal with the straightening process.