How can I get my Vtech pre coumputer powerpad working?

I have a very old Vtech pre coumputer power pad and I wish to repair it. It has a touch pad to acess the various educational games and a key board.
It takes four pencil batries to make it work.It gets on but the screen in the middle is totally blurd so I cant see anything in the middle.I also cannot acess much of the right side of the touch pad.I will be very glad if some one can help me.Thank you.