No. If you boot into bootloader mode, adb commands don't work.OK. So if I am understanding you correctly. I boot the phone into fast boot. Then type your reboot bootloader cmd.
There are 2 ways to boot into bootloader mode:
1) power down your phone;
2) hold the volume down and power buttons for about 3 seconds; and
3) release.
or
1) with your phone booted normally (i.e., into system) and with USB debugging enabled, connect your phone to your PC via USB cable;
2) open a command prompt;
3) change directory to where adb.exe is (/sdk/platform-tools); and
4) type adb reboot bootloader.