My computer monitor will only stay on for about 10 seconds and then goes off. If I turn it off and turn it on it comes on again for seconds and then shuts off. If it's not plugged into the computer I can see the floating box indicating that it's not connected but then it goes off. I can't get to the settings because it shuts off before I can see the settings. The power light stays on throughout. If there is not a computer connected to it the power light turns amber.