I have a number of the CIS  Modified 8841s.  Once they are programmed the Admin Settings is removed. How do you factory reset these phones so that you can see the MAC Address?

We are installing 8861 VOIPs on an Enterprise System.  We have had about 15% of the phone stop during initial bootup when the second button on the left and right of the display light up. The phone will not process past that.  Is there a fix for this ...