Nexus 6 not found on ADB

Question

My Nexus 6 isn't recognized by ADB, I tried on 3 different PCs, configured the drivers, I think I did all I can by myself but wheen I type "adb devices" or "adb usb", the only response I have is :

List of devices attached

Or :

error: device not found

My Nexus is plugged in with USB, I can't access to the system/storage because I erased all datas (on TWRP recovery)

If someone can help me, thank you...

Answer 1

Finally working !

I had to flash a recovery using fastboot, and I've been able to send a zip to install and it's finally working

Answer 2

Try putting it in PTP/Camera usb mode.