No power after replacing battery
I just replaced the battery in an iPhone SE (first gen) with an ifixit battery replacement kit. I’ve done this twice before on an iPhone 6 without issue. After replacing the battery, the device won’t power on at all. Shining a light on the screen does not show a faint image. There’s just no power at all, it seems. I tried open it up and just connecting the original battery (it still had some charge) to see if it would power on, and no dice. I followed the ifixit procedure exactly, making sure to disconnect the battery before disconnecting the screen.
I disconnected everything again and re-seated all the screen ribbon cables just to make sure. I had no problem seating them, I used a magnifier to look closely and ensure I hadn’t damaged any pins.
I was extremely careful at keeping track of the screws so I didn't accidentally put a longer screw in the wrong socket and thus damage the logic board.
The only thing that happen was when I first opened the case, it popped rather quickly and pulled the home button ribbon cable off. I was extremely lucky, as it had no shield over the connector, so it simply popped off without any damage. However, even if that got damaged, all I would expect is a non-functioning home button. It should still at least power on, I would hope.
I’m not sure what I can do to troubleshoot this, and would appreciated any suggestions.