Sorry I was fixing my wifes Motorola at the time and got the jobs mixed up.
Have you tried a factory reset from stock recovery (assuming the OS is still present and working)? This may allow the phone to boot and you can start custom recovery and root process again.
Does the unbrick tool not work? Are you running Windows from Bootcamp or virtualization (ie Parallels etc)? I haven't used the unbrick tool myself. I would have thought you shouldn't need ADB or Fastboot. The tool itself should do it.
Might be worth contacting OnePlus.
Well, I tried everything so yes it doesn't work.
The unbrick tool run correctly but when the phone reboot it automatically goes on bootloop.
I tried to contact them but my phone is not under warranty... they can't do anything...