Fastboot:
On your device, go into Settings → About and find the Build Number and tap on it 7 times to enable developer settings. Press back and go into Developer Options and enable USB debugging. From your computer, open a command prompt and type:
fastboot oem device-info fastboot devices
to check, if device is recognized.
To flash TWRP: Download the to your phone matching image file on https://twrp.me/Devices/ and copy the file into the same folder as your adb and fastboot binaries. Rename the image to recovery.img and type:
fastboot flash recovery recovery.img fastboot boot recovery.img
You should now be in TWRP Mode.
Just reboot:
fastboot reboot
Useful commands:
fastboot flashing unlock fastboot oem device-info
ADB:
adb devices adb logcat adb shell adb reboot bootloader
You should now be in fastboot mode.
Problems? Check FW and adb driver!
Flash:
Dalvik/ ART Cache System Data Cache