Laptop screen is barely readable, cannot not... I have a IBM think pad R51, I recently borrowed

Question

I have a IBM think pad R51, I recently borrowed it out and it was returned with a dead battery. I plugged the battery chargeing adapter into the outlet and let charge for a day. When I turn on the laptop the screen is very dull, almost completely unreadable. The laptop appears to be functioning, but I cannot navigate because I cannot see the cursor. Is there a way for me to find out if the problem is the battery or the screen backlight?