I've actually called Dell support were they guided me through a process that solved the problem.   They told me to turn off my monitor, disconnect the power cable and then press and hold the power button for 20 second. After that the problem was solved.   Thank you for your answer.
Hello, I have had this monitor for 8 months. For the past month it started turning off and on by itself while using the computer, especially when I'm gaming to a point where it becomes unusable. Also when the screen turns off, the blue light behind the monitor is blinking every second. Sometimes the monitor will not open again and I have to press the power button twice, one to turn it off completely and one more to turn it on again. When I say the monitor is turning on and off, it actually becomes black and then after a while, I'm getting screen output again, or not. I have the RTX 3070 Ti. Talked to the Nvidia forum about the drivers and we tried many things (downgrading the driver version, etc) but nothing worked and unfortunately, I don't have another monitor to test it. Many have told me it's the monitor's fault and that I should turn it back. What should I do? Thanks.
S2721DGFA, turns off and on by itself at random times