Whether or not this site is legit or not I don't know but they offer a download of the repair manual for $3.95 (http/www.supersmartelectronics.com/servlet/the-1127/Nikon-4500-digital-camera/Detail)
Someone in this thread at DPREVIEW - http/www.dpreview.com/forums/thread/1642842 - offered to send the OP a schematic manual of the camera.