The power Button wouldn't change the color. Only the small symbol near to it. It turns from grey to red if the communication fails and to green if the command was successful sent.

With Browser I mean the MicroB Webbrowser on your N900 which you're using to explore the Internet. Enter the IP adress of your DreamBox there to check if you are able to see the Webinterface. If it asks for a password you have to remove this password to get DreamRemote working. (but I don't know how to remove if it will ask for a password, it depends on your firmware and how you have set it)

Hope this helps!