iFixit's teardown report on Apple's foldable iPhone Duo says its screen failures may be linked to the hinge. According to ChainCatcher, the model received widespread negative feedback after launch, with some consumers reporting cracks in the inner screen after only days or even hours of use. iFixit said many reported failures appear near the lower-middle area of the screen's right half.

iFixit built a 3D model of the hinge using scans, teardown videos and research into Apple patents. One possibility is that a central support rod does not retract properly when the phone closes, putting excessive pressure on the screen. Another is that the curved tracks guiding hinge movement sit higher than surrounding components during folding and could interfere with the screen if they do not move as intended. iFixit did not determine the definitive cause, but said the failure area resembles the hinge's internal geometry.

The hinge consists of gears, springs and interconnected metal joints in a teardrop-shaped design, with curved tracks controlling the joints' movement. iFixit gave the iPhone Duo a repairability score of 5 out of 10 and said it may be the easiest foldable phone to repair. Its inner-screen bezel can be removed without damage because it uses clips rather than relying entirely on adhesive, and the outer screen is also relatively easy to remove.