Screen flashing green in cold conditions

Hi there,

there might be a hardware error that needs fixing going on I am afraid

But please try this to see if you can fix the issue

• Warm up the phone: Place the iPhone in an inner coat pocket close to your body heat. Let it warm up for 5 to 10 minutes. The green flashing should stop once the phone returns to room temperature. 
• Increase the screen brightness: Manually maxing out the brightness can sometimes force the OLED pixels to draw more power, which can temporarily bypass the voltage fluctuations causing the green tint. 
• Turn off Night Shift and True Tone: Go to Settings > Display & Brightness and toggle these off. They alter the screen's color calibration, which can aggravate a failing display panel. 
• Turn off Auto-Brightness: Navigate to Settings > Accessibility > Display & Text Size and toggle off Auto-Brightness

Mvaughnsullivan wrote:

Green flashing screen. Forced restart doesn’t help. Only when I am outside. Coldish

How cold? iPhone and really cold aren't good friends. But in reality I'd suspect you have the beginning signs of a screen which is about to fail. You're dealing with an iPhone from 2019, seven years ago.

Have you had the battery replaced in your phone since you bought it? Open Settings > Battery > Battery Health - if the battery is original, it likely needed to be replaced long ago, especially if it is 80% or lower. Failing batteries can and do cause issues. If the battery is failing and the screen flashes green, you could be looking at replacing the screen and for sure the battery. This wouldn't be a good investment in a phone which could be 7+ years old. I'd invest the cost of repairs into buying a new iPhone.