Why does my monitor turn on to a grey screen?

My monitor only turns on to a grey screen, it will not display anything, I’ve tried hdmi and dp. Even when it’s not connected to a computer it doesn’t say “no input” or anything like that. Just stays grey. I try to toggle the menu but still just stays grey. My computer can recognize that another display device is connected to it. The only thing I can do to it is turn it on and off from the toggle power button, then it goes from the grey screen to the black screen. When I look from behind the monitor I can see that something on the right side is lit up red, this could maybe have something to do with it? My knowledge of monitors is rather limited, please give me some answers or suggestions on what to try or what the issue may be. Thank you!