A greeting first of all, I make this visual tutorial for those who have been difficult to send your Razr I fastboot mode
I hope it will help or serve.
The end is press the Volume Down + Power and hold them until the phone restarts.
(Volume Down + Power button, leaving them to restart and dropping both, when the telephone vibrate and immediately after we see the green LED, and also the logo whatever it is)
the 2nd Form
(Volume Down + Power button, leaving them to turn off the screen, then release the power button and wait the reboot, by pressing the volume button down)
(With the phone turned off, press and hold the Volume Down button, connect the phone via USB cable to the PC, wait to restart the Fastboot menu hold the volume button down)
This is done with the phone on, off or in the process of starting or restarting.
greetings and good luck
The 1st form here the link of the video I made.
The 2nd form here the link of the video I made
Sorry no English, Audio in Spanish, helps to put them subtitles.
SORRY FOR MY BAD ENGLISH