No idea at all what you're saying here. It's FXZ, for one. And the FXZ posted in this thread is the latest for the XT926. GPT failure can be caused by a whole bunch of reasons. Just saying it failed without telling any more information is meaningless. Could be caused by using the wrong USB cable, wrong USB port, old drivers, wrong version of RSD, low power state on the phone, etc, etc. It's not possible to know why it failed in your case without more information other than stating it failed.
Sorry yes FXZ - realized after I read back my own post.
What more information to provide? Battery shows ok in Fastboot, USB Cable is original motorola supplied data cable that came with the phone. (Don't know what it means to have 'wrong USB port' - aren't they all same - this is Win7/hp laptop).
I was using RSDLite 6.1.5 but switched to 6.2.4 and retried. Had installed latest motorola drivers; tried installing the same from link you provided and it confirmed same version (reinstall with the mediafire msi gave repair/remove 6.4.0 install options and selecting repair 90% of the way through says "account exists" and ends - other than the 'account exists' part it seems to suggest everything is fine).
Below is SWDL snippet for latest run. Also attaching full SWDL. Thanks a lot for your help!
02/01/15 11:00:15 --------------------------------------------------------------------------------
02/01/15 11:00:17 New Log Started For Software Download.
02/01/15 11:01:14 Arrival, interface=28(0x0), device id=1636460.
02/01/15 11:01:56 The FlashLog key is turned off.
02/01/15 11:02:03 Multi upgrade started for 1 phones
02/01/15 11:02:03 [Device ID: 0] 1/20 oem fb_mode_set
02/01/15 11:02:03 [Device ID: 0] 2/20 flash partition "gpt.bin"
02/01/15 11:02:04 ERROR: 2/20 flash partition "gpt.bin" -> Phone returned FAIL. - on device ID 0.
02/01/15 11:02:04 [Device ID: 0] 2/20 flash partition "gpt.bin" -> Phone returned FAIL.
02/01/15 11:02:04 ERROR: Failed flashing process. - on device ID 0.
02/01/15 11:02:04 Multi upgrade finished.