Chris,
If you are hearing clicks when you turn the dial, then we must assume the battery is fine because the click noise comes from the speaker. If there is no display or dialtone when you press the handset button, then the phone almost certainly has a fault. If this is the case a replacement PCB would be required. However, if this is a Mark II version which has a handset socket at the top of the phone, then you may wish to press and hold the centre dial button for at least 3 seconds, then do the same action a second time and see if the phone comes back to life.