Screen replacement tested great, then black after completed install
After removing the old broken screen from the Moto X4 XT1900-1, I connected the replacement screen (Glass and Digitizer) before proceeding to install the precut gasket. It worked perfectly.
Then, I turned if off, prepared the surfaces, applied the gasket, and reconnected the ribbon connectors. The fingerprint sensor created vibration, but the screen stayed black. I repeated the sequence a half dozen times: turn off (press/hold power button, then press/hold power and down volume buttons), disconnect screen ribbon, reconnect ribbon, restart, sound resumed and fingerprint sensor vibration. Infant failure of the replacement part, or other damage?
On close inspection, there was a loose tiny plastic cube near the latch that fell off to a slight touch. In its place, previously beneath the cube, were 4 tiny metal connections. I reviewed a YouTube video of the repair, and saw a difference (image attached), suggesting a possible cause. Apparently two of the cubes are missing on my phone; my guess is that these cubes may have been jumpers connecting the 4 connections somehow. I was unable to find the tiny cubes to inspect and see if they are jumpers. If they are, it might explain the failure to perform, and I could repair with solder if I knew more about their function. I am reticent to remove one of the remaining 3 for inspection, and these cubes may have nothing to do with my problem. If so, it is probably a known production issue. The preview of this posting did not preview the uploaded image, which is an illustration of the area by the socket and a graphic of the potential issue described in this paragraph.
The failure could be an “infant” failure of the component, which is not very unusual. Before returning the part, I am hoping that someone has an idea. Because IFIXIT is a Motorola partner, I’m hoping for guidance from IFIXIT and Motorola experience. Meanwhile, I’ll try the disconnect/reconnect cycle more times in the off-chance that it might clear some debris that might have gotten into the socket.