Remov the battery and check the battery terminals as well as the terminals in the camera and look for any corrossion, if only limited use over the last four years then it is possible the camera has been left extended periods with a battery that will go flat even if not used.
The terminals should be clean and shiney
The contacts need to be shiney, not dull... If looking good then it may be the battery has died... The average life of these batteries are 4 to 5 years... Less if not used much... I would take the camera to a store that sells these batteries and get them to test a new battery in the camera...