Hi, I have an old Lifebook C2240. Does the battery need to be installed for it to turn on? Or can it be turned on with the battery removed and plugged into AC power? My unit is not turning on whether the battery is installed or not. I want to check if the battery needs to be installed or not for it to turn on. My guess is the battery is not needed but I want to make sure.When I remove the battery it also does not turn on. I hit the ON button many times in all cases. No lights. No fans. Nothing. Any ideas? My guess is the internal power circuit is damaged.