Chosen Solution
Hello ! So I have an iPhone 6 Plus that I had to replace screen on (months ago) and it was working fine until about two days ago. It started doing this no signal/ no service mess but if I bent the top of the phone by signal came back. I opened my phone (which I’ve done confidently on many of my iPhones) I was looking for the antenna and disconnected the power cable to my sleep/wake button. I plugged it back in when I realized I never turned my phone off but it wouldn’t work, so I unplugged the battery. I plugged everything back on and now my phone won’t turn back on. I tried plugging it up to the charger, a hard reset. Nothing. And there is a weird warm spot or the top of my phone near the camera
Can you confirm if you removed the screen assembly or not, it’s not clear in your question? If you did remove it without disconnecting the battery first, you may have damaged the backlight circuit. Follow the recommendations by @rayeasom but in addition I would also do the following: visually inspect the connectors with a magnifying glass or jeweler’s loupe to see if there is any damage to the connectors or surrounding components.verify that you have put the right screws in the right places. iPhone logic boards can be damaged by putting longer screws in the wrong place. Follow this guide.with the phone “turned on”, put a bright flashlight on the screen and see if if faint image is visible. If you can see an image, that would be indicative of a defective backlight circuit. Regarding your original “no signal” problem, I would be concerned about the fact that torquing the frame made it work temporarily. The iPhone 6 Plus is well known for have a bendy frame and it sounds like your device has had its share of flexing. You may have some latent logic board problems that will continue to surface.
id start by checking all the cables are connected properly and free from any dirt/obstructions. Connect your phone to a computer that has already been “trusted”, does iTunes recognise your phone if not try a new battery, if it does the fault lies either with the display or the display IC.
