I'm not exactly sure what you are asking. To get to the fastboot menu on the phone, with the phone off, press the power and up and down vol buttons simultaneously, then let go. From there you can choose to power on normally, go to the ap fastboot menu, recovery, or some other choices. If you are talking about the moto-fastboot process that can return you to stock, make sure you have the current rsd lite and the proper moto drivers (32 or 64-bit) installed. To what 'fastboot button' on your computer are you referring?
I was able to get it unbricked via rs lite but I had a fastboot sdk but when I run any exe or bat etc it will initiate the command shell on my computer and disappear. I did eveything avgf mng sdk mng platform but I was lucky enough to get the files to install via lite.
I had everything in the from right from C: target at a loss I was almost ready to redo my system to factory
You have to initiate it through a command shell... hold shift then right click the window where your fastboot file is... select open command prompt here for on windows.