The most often cause of Minecraft servers failing to turn on is an unaccepted Mojang EULA. When a server is turned on for the first time, this must be done through the control panel and not the billing panel. To see login details, go to your main billing panel page, and click on the row containing the server (not the manage button). This way, you will see a prompt allowing you to accept the EULA. Once you turn on your server this way, power controls will work from your billing panel as well!