Hello. My name is***** can help you with your question.
The one thing that I didn't see whether you tested was connecting those monitors to a different computer so you can find out if it is with the graphics circuit in the computer or if it is a problem from the HDMI output to the monitor or the monitor itself. If you can do that, that would help us to narrow it down. It sounds to me like your monitors may have failed but I'd like to make sure before just saying that is what is happening.