T57W will not factory reset to autoprovision!

[bill@wesimplifyit.com]

We left RingCentral and are trying to add the T57W to Microsoft SIP servers. We have factory reset the phone SEVERAL TIMES but it keeps booting into the RIngCentral servers! We contacted RIngCentral to remove the phone (they state they did). Now the phone shows PU-mvd on the screen but I cannot provision it to Microsoft's SIP servers. After entering the correct data and clicking AutoProvision Now (either from the phone's LCD screen OR the web interface) NOTHING happens! If I restart the phone it still boots to the RingCentral info (the Auto Provision screen data changes back to Ring Central servers instead of the Microsoft server information I entered).

How can I get rid of this RC configuration once and for all???