I have used 2 X-700s and both of them, as they got older, locked up the shutter. I took them to the repair shop and the technicial was able to free the shutter and the camera worked fine after that. I think it only happened to both cameras one over the 20 years I used them.
If it's as simple as a new battery, which it most likely from condition of your camera, simply replace them and it should wirk fine. The shutter will not operate without functioning batteries. You can tell if the batteries are dead by turning it on, placing your finger on the shutter switch to activate the meter, and then look in the viewfinder and see if the leds are lighting up in it.