Chosen Solution
Hey, my iPhone 6 doesn’t wake up when it’s on standby. If I press the home button or standby button the backlight is enabled but the screen stays black. I forced a hard reset by using dfu-mode and tried different batteries and displays, but it still stays the same. Do you have any additional ideas?
Does your display ever work, like when you boot it from a shutdown; or is it always showing the backlight but no image when it should be “on”? Try connecting it to 3uTools (for Windows) when the display isn’t working to see if the phone is fully (or still) booted. If 3uTools sees the phone, then you probably have a LCD driver issue. This requires a micro-soldering repair.
Most likely it is a broken LCD. The backlight turning on with no image means that the connections between the cable and the LCD at the top of the screen under the front camera flex has been broken. This can be fixed by replacing the screen
