Sorry, but I don´t know how execute the command "fastboot flash recovery twrp-3.1.1-0-land.img" in fastboot mode.
Could you tell me?

:crying:
First, you need to download an adb and fastboot package (just google...)
Then you need to extract it somewhere on your pc.
Then you copy your "twrp-3.1.1-0-land.img" into the same folder where adb.exe and fastboot.exe is located.
Then you rename your "twrp-3.1.1-0-land.img" into "recovery.img".
When you have Windows 10: Hold shift and rightklick somewhere in the white (whithin the adb-folder) -> "open power shell window here"
In Power shell just type "./fastboot flash recovery recovery.img"
If you get "waiting for device" you have to install the google adb driver: download it (google), extract it somewhere and install the driver manually via device manager - when you get to choose the driver, choose "android bootloader device".
Windows 7: Hold shift and rightklick somewhere in the white -> "open command prompt here".
In command prompt: "fastboot flash recovery recovery.img"
If you get "waiting for device" you have to install the google adb driver: download it (google), extract it somewhere and install the driver manually via device manager - when you get to choose the driver, choose "android bootloader device".
And it´s clear: your device has to be in the fastboot mode (pwr + vol-)
Chears!