Originally Posted by vmin81
what is the main function of ((vendor.xml)) ?? and why i need to delete it ?? and what it will happen if present ??
That is the file that identifies the OS as being for a particular carrier's phones. Makes no difference if the phone is locked or unlocked -- the carrier code is in the firmware. If you delete vendor.xml, then you can install the OS on any carrier's phone. When the vendor.xml file is present, the OS will not install on the other carriers' phones.
The important thing to remember when upgrading your OS is to follow the instructions exactly as written. Failing to do so will result in failure to complete a successful upgrade.