I wouldn't exp[ect the power pack to affect you whilst you have the mains plugged in...............is the machine very old? I would normally expect them to have a bypass to let you run from mains supply.

Try taking the battery out and see if it runs from the mains. Also charge the battery then unplug the machine and just leave it on and see how long it lasts.

Yes, a webpage script could do what you are describing, but there wouldn't seem to be much point. Can you try the page with another PC?