Chosen Solution
I replaced the screen on my iPhone 6s. After I attached the first ribbon cable to the phone, the second cable touched the pins and sparked and smoked for a second. I proceeded to finish, and the screen is now not turning on….What do I need to replace?
You probably shorted out the backlight circuit. that’s what the spark was. You have to disconnect the battery before disconnecting or reconnecting the screen assembly otherwise the backlight circuit has a tendency to blow. On the LCD connector, VCC_MAIN and GND are adjacent pins so if the connector is not perfectly lined up, it will short. If your lucky, it’s just a filter however sometimes the damage goes upstream and blows thew diode and or driver IC. This requires a micro-soldering repair. To be certain, connect your phone to an iTunes enabled computer. Shine a bright flashlight on the screen and if you see a dim image, the the problem is the backlight circuit.
Clean the contacts and try replacing the screen again with a new screen.
