Chosen Solution
So I recently replaced my iPhone 7 Plus screen as it was cracked all over, and the LCD was turning black in many spots. I replaced the screen and everything was working great. I got functionality back in my front camera and such, but I’m having an issue with the phone randomly lighting up to the lock screen like I’ve clicked the power button. If I remember correctly, near the end of the other screen’s life, it was doing this. And also now, the power button is also kindly weird, if I hit it in a certain way or length of time, it cuts off. I thought the screen replacement would fix it, but apparently not. It still works great, but the battery drainage is for real. I was curious if anyone knew what could be causing this?
Are you sure it isn’t due to the raise to wake feature being turned on? You can access that setting with the help of this linked guide from apple: https://support.apple.com/en-au/HT208081
This is going to be water damage. My crystal ball says that your cracked screen had degraded to the point that a few drops of water got into the phone at the top left side of the phone. You likely have some corrosion around the power button and nowhere else in the phone. This corrosion is doing all of the things you are complaining about: Rapid battery drain—because some line is short from corrosion Screen turns on by itself—-whenever the corrosion drops the power button line to zero (as if you pressed the button)
Power button is wonky—-due to corrosion at the power flex.
This is a really common spot for a drop of water to land, and it is sometimes the only spot that gets water in a 7plus.
Solution: Take the screen back off after disconnecting the battery, remove the shield covering the power flex connector on the far left end of the motherboard and clean it with a qtip and alcohol.
