First check the simple mechanical and contact issues. Clean and inspect the battery contacts inside the camera, as dirty contacts or a weak battery terminal spring can prevent power from reaching the camera.

Also inspect the battery door and CF card door closely. These doors usually have small tabs or prongs that press internal switches when the doors are fully closed. If either tab is broken, bent, or not engaging the switch, the camera may think a door is open and refuse to power on.

If the contacts look good and both door switches seem to be working, there is not much else you can easily diagnose at home. On a camera this old, further repair is likely to require professional service and may cost more than the camera is worth.