You say it won't power up at all so I assume that means it won't boot by the battery either. Do you know the state of charge on the battery. If the power adapter has been dead you may have been running on battery until you drained it. I would try another adapter --preferably borrowed not purchased first. If it powers you have your answer--if not I would think you could eliminate the battery as a cause of your problem. You may want to open your computer to check for physical signs of damage and for that reason I am including a link for opening your computer. Good luck Ralph
http://www.irisvista.com/tech/laptops/ToshibaM45/Satellite_M45_disassembly_1.htm