On Sunday, repair company iFixit released its teardown of the iPhone Duo, including a video detailing the specific parts inside and what to look out for if people need to fix their $1,999 phone one day—maybe sooner than they think.

The culprit behind the screen breaking hasn’t been officially verified yet, but iFixit has a theory. Along the hinge, a display cable passes across the center of the hinge. In iFixit’s stress test simulation, the center support bar along the hinge fails to get out of the way as the screen folds, making a stress point right in the middle of the screen that could be leading to those cracks.

The phone got a provisional repairability rating of 5/10, though that score may be updated to factor in how Apple supplies replacement parts. A 5/10 doesn’t sound great, but it’s actually the highest repair rating iFixit has given any foldable phone.

“The state of foldables today is one of the hardest engineering challenges across a number of disciplines out there in the market today,” iFixit CEO Kyle Wiens said at an event the day before Apple announced its folding phone in September. “It is the pinnacle of material engineering and materials science. It is ludicrously difficult to accomplish this.”

The iPhone Duo earned good marks on some repair fronts. The battery and back panels are straightforward to remove and replace. The outer trim comes off in one piece. The 5.4-inch front screen comes off easily enough. Disassembling the pieces and putting everything back together is doable too, since almost everything is secured with brackets and screws you can remove and reuse.