most likely the battery is flat, i always take it out if i leave my unplugged for more than a week, have a look in radio shack or online for one, they have a 6 digit on them check the code and get one (the code should be CR2032)
what black window loading screen? the black screen with the Windows loading bar at the bottom?
most likely the battery is flat, i always take it out if i leave my unplugged for more than a week, have a look in radio shack or online for one, they have a 6 digit on them check the code and get one (the code should be CR2032)