I'm pretty new to raspberry pi, and it always used to work fine, but I've got a new monitor, the BenQ GW2270, and I set my raspberry pi 4 up using the micro-hdmi to my monitor's hdmi port, and when I switched it on, I saw the rainbow coloured switching on screen, but then it just went black for a few seconds, then my monitor just said no signal, and I don't know why. Thanks for helping!
Try the following:
- Use the old monitor to change the resolution to 640x480 and frequency of 60.00Hz (through Screen Configuration)
- Make sure you are using the HDMI closest to the power input
- If possible, plug the old monitor into the first HDMI and the new one into the second HDMI and see if they both display stuff.
Hope this helps you fix the problem.