Panasonic SV-3800 error in tape loading

My Panasonic SV-3800 DAT was my reliable studio backup until I began using USB hard drives a couple years ago. I left it in the rack powered off for several years, turned it on recently and fed it a tape and it will not load. The tape drawer pulls the tape inside the machine and I hear some motors whirring, but it never loads the tape. Instead, the word 'Error' appears in the display. New tapes and old tapes experience the same failure, and will not load. I can eject them fine and open and close the drawer fine. Any ideas what might cause this problem or what may resolve it? Thanks.