[Moto G Q&A, Help & Troubleshooting] grabnork:
I literally JUST unbricked my Moto G XT1032 after searching for a long while and piecing instructions together. Here's how:

PREPARATIONS

1) Download XT1032_RETAIL-BR-SS_4.4.4_KXB21.14-L1.40_42_cid12_CFC_1FF.xml.zip

This is the stock firmware you need to flash. I haven't tried it with anything else. The instructions that follow are specific to this file, although you should be able to follow the general idea to install different ROMS.

Get the firmware (or a different one) here: http://xdaforums.com/moto-g/general/index-moto-g-falcon-factory-firmware-t3110795

2) Ensure that you also have the correct Motorola drivers for this phone. Download 32-bit or 64-bit versions depending on your PC.

Get them here http://xdaforums.com/showthread.php?t=2550635

3) Download MFastBoot v2

Go to http://xdaforums.com/general/rooting-roms/using-mfastboot-exe-to-unbrick-motorola-t3203518

or simply download the file at (https://mega.nz/#F!xUh10AAD!5NvRwDf6eAfjE3bUWZfk7g)

Note: From what I've experienced, you CANNOT use normal Fastboot on this phone. You will keep getting errors such as Failed (remote failure). You have to use MFastBoot.

Open the downloaded file. There will be two other zip files inside it. Extract all contents of mfastboot-v2.zip to a folder of your choice.

4) Download TWRP Recovery. It's usually a good idea to have a recovery, even though it's not used to flash the ROM.

Get the highest version of it here: https://dl.twrp.me/falcon/

Extract the .img file to the SAME folder as where you extracted mfastboot and rename it to twrp.img (not really necessary, but it's easier to type into the command prompt).

5) Extract all contents of XT1032_RETAIL-BR-SS_4.4.4_KXB21.14-L1.40_42_cid12_CFC_1FF.xml.zip to the SAME folder as where you extracted mfastboot.

6) Ensure the phone is off. Hold VOL DOWN first, and then press POWER button for about 5 seconds, then release POWER button before releasing VOL DOWN. You should be in fastboot mode. Plug the USB cable into the phone now.

If you see Device is locked. Status 0, follow the instructions in the UNLOCKING THE BOOTLOADER section.

If you see Device is unlocked. Status 3, continue to step 7.

FLASHING THE FIRMWARE

7) Open the folder where everything has been extracted to.

Hold CTRL+Shift and right click in an empty area of the folder. You will see a normally hidden option to "Open Command Window Here". Select that option and a command prompt window will open. If you are not seeing this, you may not have administrative rights on your account.

Type this into the command prompt: mfastboot reboot

I'm unsure if this is required or not, but mfastboot wouldn't work unless I rebooted it from the command prompt before any other instruction.

8) This is the step where the TWRP recovery and ROM files are flashed.

Type the following into the command prompt, pressing enter after each line. Alternatively, just copy each line and right click>paste into the command prompt. Credits to AgentChaos for the following:

mfastboot flash partition gpt.bin

mfastboot flash motoboot motoboot.img

mfastboot flash logo logo.bin

mfastboot flash boot boot.img

mfastboot flash system system.img_sparsechunk.0

mfastboot flash system system.img_sparsechunk.1

mfastboot flash system system.img_sparsechunk.2

mfastboot flash modem NON-HLOS.bin

mfastboot erase modemst1

mfastboot erase modemst2

mfastboot flash fsg fsg.mbn

mfastboot erase cache

mfastboot erase userdata

mfastboot flash recovery twrp.img

If you used normal fastboot at this step, it will fail and give you an error of "Failure (remote failure)". or it will say it could not find or write to some directory.

Hopefully it does not fail, and should say OKAY after writing each file. This step will take several minutes.

If you used a different firmware than I did, you will have to flash the correct files to the correct directories, and they MAY be different than the ones listed above. I think (but I am not sure) that the only difference would be having to flash and additional sparsechunk.3 or 4. I would not suggest doing this if you aren't sure.

After all files have been flashed, do one final mfastboot reboot and press VOL DOWN and select Recovery, then press VOL UP to start it. You should see the TWRP recovery screen. The screen may glitch out but otherwise be operable. You can press REBOOT then SYSTEM to start the phone normally.

I hope this has been helpful.

UNLOCKING THE BOOTLOADER

A) Open the folder where everything has been extracted to.

Hold CTRL+Shift and right click in an empty area of the folder. You will see a normally hidden option to "Open Command Window Here". Select that option and a command prompt window will open. If you are not seeing this, you may not have administrative rights on your account.

Connect the USB and type this into the command prompt: mfastboot oem get_unlock_data

You will see a string of characters that looks like:

(bootloader) 0A40040192024205#4C4D3556313230

(bootloader) 30373731363031303332323239#BD00

(bootloader) 8A672BA4746C2CE02328A2AC0C39F95

(bootloader) 1A3E5#1F53280002000000000000000

(bootloader) 0000000

B) Go to Motorola's unlocking bootloder tool website here:

https://motorola-global-portal.custhelp.com/app/standalone/bootloader/unlock-your-device-b

You will need to create an account with a legitimate email account, which takes 1-2 minutes.

There is a text box on Motorola's site where you need to type the exact combined code you received from top to bottom with symbols included, but don't include "(bootloader)". Agree to their terms and services.

C) You will receive an email with your bootloader unlock code.

Go to the command prompt and type: mfastboot reboot to reboot the device. Alternatively, just reboot it manually.

Type: mfastboot oem unlock UNIQUE_KEY where UNIQUE_KEY is the unlock code you received. The screen should go black and you should see the word "Unlock...". The phone may stop responding at this point, in which case simply wait 1-2 minutes to ensure it is finished doing what it was doing, and then manually reboot it.

Boot into fastboot again and now your device should say "Device is unlocked. Status 3"