Chosen Solution
I was using my SE when suddenly the display froze, developed a really strong red and purple tint, and got lines all over it. Then after about fifteen seconds it faded to black. I force shut it down but it didn’t seem to turn back on. Later on I plugged it into my computer and iTunes would recognize it(but wouldn’t connect because I couldn’t unlock it). I talked to Apple Support for a long time and after trying to update it in recovery mode, they said that it’s likely that the display broke. But my display’s in very good condition, and I just swapped it out with one from another iPhone SE, and I’m still not getting any picture or backlight from it, and the display from my phone works perfectly fine on that other SE. I’m pretty sure that the phone right now is stuck in the setup menu after updating it to iOS 11.3 (which it was already in), so I can’t use the mute switch or Siri or QuickTime streaming to find out if anything else is working (iTunes was being difficult about recognizing it for a while, but now it is). This is seeming to not be a display problem, right? Really hoping this is something I can fix without needing to take it into Apple or buy a new logic board or something. Thank you.
If it were just a black screen, I would say that it may be stuck in DFU mode. However the purple fade and lines seems more like a hardware issue than anything else. I would download 3uTools and connect it again to see what 3uTools determines about the state of your device. If it is in recovery mode, you will be given the option of taking it out of that mode. If it isn’t, you could try to enter DFU mode and do a fresh install of iOS 11.3. Unfortunately, iOS 11.2.6 is no longer signed so you can’t downgrade. If none of that works, then you likely have a hardware issue on the logic board, which will require a micro-soldering repair.
