Installing TMobile ROM on an AT&T branded phone topic

I have an at&t branded phone. I recently switched to T-Mobile and would like to get T-Mobile ROM installed on it.

I started with a phone which was NOT rooted, had stock AT&T rom.

I have done the following so far:
*

1. Unlocked my boot loader - worked flawlessly


2. Installed TWRP - worked flawlessy


3. Attempted to install Super SU - I think it worked


4. Attempted to install a T-Mobile ROM - Getting a "Error flashing zip" error

I download official T-Mobile ROM installer from HTC website. I let the installer run until I saw "Rom.zip" in the temp folder.

A website on google told me that i can use this file to flash my phone. I did have some doubts about this file as I am able to unzip only half the file's contents using winrar. But anyways, I went ahead and used this ROM file.

I rebooted my phone in Recovery mode (TWRP). I clicked on Install and selected rom.zip from my SD Card. When I attempt to install rom.zip, I received following messages:

Installing '/external_sd/tmobile_rom.zip'
Checking for MD5 file...
Skipping MD5 check: no MD5 file found
Error flashing zip 'external_sd/tmobile_rom.zip'
Updating partition details...
....done

I tried a few different ROM's I found on the internet with the same error message.

So now I am stuck with no OS on the phone. I can only go to bootloader or TWRP.

If someone can suggest a more appropriate ROM file, I can give that a try.

xda-developers