I have a hp 24

Question

I have a hp 24 h2408w monitor. I switch computer and when I booted the computer the monitor said Desact.monitor. I try to put it in quickview for adjustments by pushing the button on the bottom that now it went into some sort of test mode. In a full screen it goes from green to blue to white to red to black, over and over. This is all the monitor will do. It does not matter on if it hook to a computer or not. This is all that it does. Help