Chosen Solution
I bought an iPhone 6 off eBay that needed a new screen. I replaced the screen and it turns on and when plugged in iTunes it shows up, but the screen still doesn’t show up.
I would agree that it sounds like the backlight filter. You will have to have someone who can micro solder replace the filter for you unless you have the tools and expertise. Good Luck
Always start simple. Pull the screen, disconnect the battery, then disconnect and clean the LCD connectors. Clean them thoroughly with alcohol. Take a look and make sure you don’t have any bent pins, then reconnect everything and plug it in. Hopefully you see an apple. If not… Hold down power and home for at least 30 seconds. See if you get an apple. Look closely at the screen to see if its just really dim. If that doesn’t work, try your original screen. Does that one work? If you try all of this and still can’t see an apple, then its time to move on to board level stuff.
