After disassembling the iPhone Duo, iFixit pointed out two potential reasons for cracking at the screen crease, but still appreciated this folding phone.

Electronics repair site iFixit and a number of technology YouTubers reviewed the components as well as a CT scan combined with a 3D model of the hinge assembly. They found that the center support bar may not have lowered properly when the user folded the device. As a result, the fold is pressed directly onto the support bar, creating a contact point that makes the screen vulnerable to damage and cracking.

Another cause could be the hinge's curved rails, Apple uses curved rails to keep the screen slightly curved when opening and closing. However, one of these rails sometimes does not retract into the correct position, creating incorrect force on the display cable area and the thin glass layers inside.

However, experts emphasize that this is their assessment based on technical analysis and reality from a number of faulty machines. The recorded screen failure rate is still low, not a mass incident.

In addition, iFixit still gives the iPhone Duo a repairability score of 5/10, the highest level for a folding smartphone, surpassing the Galaxy Z Fold 8 or Pixel 11 Pro Fold which reached 4/10.

Apple gets high scores thanks to some clever design improvements, like making removing the battery easier thanks to an adhesive layer that automatically peels off when a small electric current is activated through the circuit. The outer screen and protective layer are easy to replace, and the outer protective nano-texture coating can also be changed at a cost of 19 USD with AppleCare+ and 49 USD without using this service.

However, repairing the internal screen is a big challenge due to its complex structure of 10 layers and dense amount of glue. More importantly, the cost of replacing Apple's folding screen is up to 999 USD, nearly half the starting price of the device. This level is much higher than the figure of 560–580 USD being applied by Google and Samsung for folding devices.

iPhone Duo users are advised to be careful during use, avoid letting dust get into the hinge slot and should not try to force the device to fold if they hear strange noises.

iPhone Duo officially went on sale on October 23, but after only one day, the device began to show limitations, the most serious being screen cracks and streaks. Images shared online show that the defective machines all have the same stripe in the middle of the hinge and the way the stripe spreads is also the same.

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