Is this all batteries? If so a clean of contacts on the camera and battery may be in order, and will do no harm anyway, and the spring loaded contact on the battery, that is for the data, it is still springing isn't it?
On a battery reset I find it sometimes requires the prism and back to be removed as well before the reset but either way it needs some dexterity if performed solo and I find a assistant is useful, willing or press ganged doesn't seem to matter.