Again Issues upgrading Firmware T46G

[Jeroen]

I have again Issues Upgrading T46G firmware

My Suppier gave me both Broadcom 28.71.188.x firmware Phones
and Non Broadcom 28.72.0.x firmware versions

For our 3CX PBX I want to use the 28.72.0.45 firmware, and this fgirmware only for now.

I learned how to disable te securtity certificates and Reset the firmware to factory Default. Still, i cannot put the required 28.72.0.45 firmware on to the phones: While upgrading it still whines about a wrong OEM version.

Given My supeer powers of deduction, I even tried to load the 28.73.193.45 on the Broadcom phones (guessing it isthe broadcom version of the 28.72.0.45 firmware)

So the question:
How can I reset the T46G phones, and make sure i can load any required ROM in them with out a 3rd party intervention (like lydis).