[Paid Software Announcement and Discussion] PiousInquisitor:
We need to clarify a few things: Only fastboot, mfastboot and mofo work in bootloader/fastboot mode. ADB does not. USB Debugging is required for ADB. You should have it on while we work thorough this though since we will use ADB to figure out your issues.

This is usually means you need a new udev rule. Create a new text file in /etc/udev/rules.d/ called '51-android.rules'. Within this folder paste the following and save it.

#Acer
SUBSYSTEM=="usb", ATTR{idVendor}=="0502", MODE="0664", GROUP="plugdev"
#ASUS
SUBSYSTEM=="usb", ATTR{idVendor}=="0b05", MODE="0664", GROUP="plugdev"
#Dell
SUBSYSTEM=="usb", ATTR{idVendor}=="413c", MODE="0664", GROUP="plugdev"
#Foxconn
SUBSYSTEM=="usb", ATTR{idVendor}=="0489", MODE="0664", GROUP="plugdev"
#Fujitsu & Fujitsu Toshiba
SUBSYSTEM=="usb", ATTR{idVendor}=="04c5", MODE="0664", GROUP="plugdev"
#Garmin-Asus
SUBSYSTEM=="usb", ATTR{idVendor}=="091e", MODE="0664", GROUP="plugdev"
#Google
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", MODE="0664", GROUP="plugdev"
#Haier
SUBSYSTEM=="usb", ATTR{idVendor}=="201e", MODE="0664", GROUP="plugdev"
#Hisense
SUBSYSTEM=="usb", ATTR{idVendor}=="109b", MODE="0664", GROUP="plugdev"
#HTC
SUBSYSTEM=="usb", ATTR{idVendor}=="0bb4", MODE="0664", GROUP="plugdev"
#Huawei
SUBSYSTEM=="usb", ATTR{idVendor}=="12d1", MODE="0664", GROUP="plugdev"
#K-Touch
SUBSYSTEM=="usb", ATTR{idVendor}=="24e3", MODE="0664", GROUP="plugdev"
#KT Tech
SUBSYSTEM=="usb", ATTR{idVendor}=="2116", MODE="0664", GROUP="plugdev"
#Kyocera
SUBSYSTEM=="usb", ATTR{idVendor}=="0482", MODE="0664", GROUP="plugdev"
#Lenovo
SUBSYSTEM=="usb", ATTR{idVendor}=="17ef", MODE="0664", GROUP="plugdev"
#LG
SUBSYSTEM=="usb", ATTR{idVendor}=="1004", MODE="0664", GROUP="plugdev"
#Motorola
SUBSYSTEM=="usb", ATTR{idVendor}=="22b8", MODE="0664", GROUP="plugdev"
#MTK
SUBSYSTEM=="usb", ATTR{idVendor}=="0e8d", MODE="0664", GROUP="plugdev"
#NEC
SUBSYSTEM=="usb", ATTR{idVendor}=="0409", MODE="0664", GROUP="plugdev"
#Nook
SUBSYSTEM=="usb", ATTR{idVendor}=="2080", MODE="0664", GROUP="plugdev"
#Nvidia
SUBSYSTEM=="usb", ATTR{idVendor}=="0955", MODE="0664", GROUP="plugdev"
#OTGV
SUBSYSTEM=="usb", ATTR{idVendor}=="2257", MODE="0664", GROUP="plugdev"
#Pantech
SUBSYSTEM=="usb", ATTR{idVendor}=="10a9", MODE="0664", GROUP="plugdev"
#Pegatron
SUBSYSTEM=="usb", ATTR{idVendor}=="1d4d", MODE="0664", GROUP="plugdev"
#Philips
SUBSYSTEM=="usb", ATTR{idVendor}=="0471", MODE="0664", GROUP="plugdev"
#PMC-Sierra
SUBSYSTEM=="usb", ATTR{idVendor}=="04da", MODE="0664", GROUP="plugdev"
#Qualcomm
SUBSYSTEM=="usb", ATTR{idVendor}=="05c6", MODE="0664", GROUP="plugdev"
#SK Telesys
SUBSYSTEM=="usb", ATTR{idVendor}=="1f53", MODE="0664", GROUP="plugdev"
#Samsung
SUBSYSTEM=="usb", ATTR{idVendor}=="04e8", MODE="0664", GROUP="plugdev"
#Sharp
SUBSYSTEM=="usb", ATTR{idVendor}=="04dd", MODE="0664", GROUP="plugdev"
#Sony
SUBSYSTEM=="usb", ATTR{idVendor}=="054c", MODE="0664", GROUP="plugdev"
#Sony Ericsson
SUBSYSTEM=="usb", ATTR{idVendor}=="0fce", MODE="0664", GROUP="plugdev"
#Teleepoch
SUBSYSTEM=="usb", ATTR{idVendor}=="2340", MODE="0664", GROUP="plugdev"
#Toshiba
SUBSYSTEM=="usb", ATTR{idVendor}=="0930", MODE="0664", GROUP="plugdev"
#ZTE
SUBSYSTEM=="usb", ATTR{idVendor}=="19d2", MODE="0664", GROUP="plugdev"

Technically you could just use the Moto part but if you get a new phone you will need the specific part for that phone. I suggest just copying it all.

Then change the permissions of the file and restart udev. Note these commands need to be run as a superuser.

chmod a+rx /etc/udev/rules.d/51-android.rules

restart udev

service udev restart

Now with USB Debugging on, plug your phone in (while its on and booted up) and make sure you allow ADB (from the pop up on your phone) to run on your computer.

Open a terminal and type:

adb kill-server
adb devices

If you get a serial number you are good. Fastboot should also work as well as mofo.

Let us know how it goes.