My first DIY smartphone repair project was off to an inauspicious start. I’d successfully removed the back of the HMD Skyline, but the next instruction called for a T3 screwdriver bit. I had a T4 bit, which worked well enough to turn the screw that popped the corner of the phone’s back panel up. But a T4 was just too big for the tiny screws holding the battery connector cover in place. I needed that T3. The Skyline is one of HMD’s latest user-repairable phones . It’s a midrange phone, one of