Many functions appear to be disabled

I recently acquired a business ownded by an elderly couple, they used two Sharp ER-A530's that are being used in an Ice Cream SHop, it appears that they had someone disable numerous aspects of the registers. As an example I was trying to program a discount button and while I can program the button, when I use it in op mode, it throws an error. ANother example is that voiding and refunding are not functional, I tried to enable them in Program mode, and I get an error while trying to change their status. It appear as though ability to enable to program many useful keys/functions has been disabled, but I have not been able to find a manual or index that explains how to enable them.... In other words How do I enable the ability to enable voids or refunds?
Thansk very much for your help, I am growing desperate.