Hi there,
I just got a new Yubikey NEO-n and was trying to configure it for U2F+CCID mode using ykpersonalize. Nothing seemed to work with the U2F demo (I never got it working at all). I couldn't use the Yubikey NEO Manager because it won't even install on OS X Yosemite.
I tried a few different settings, and after awhile ykpersonalize reported it could no longer see the Yubikey at all. I did not physically remove it during this process:
Code:
$ ykpersonalize -m6
Firmware version 3.3.0 Touch level 1285 Program sequence 1
The USB mode will be set to: 0x6
Commit? (y/n) [n]: y
$ ccccccdufvecnvhecdvdbnkfnccieuulbbenudictgbj
zsh: command not found: ccccccdufvecnvhecdvdbnkfnccieuulbbenudictgbj
$ ccccccdufveclfevhrdurjfifjrrujejntkllnrikejf
zsh: command not found: ccccccdufveclfevhrdurjfifjrrujejntkllnrikejf
$ ykpersonalize -m5
Firmware version 3.3.0 Touch level 1285 Program sequence 1
The USB mode will be set to: 0x5
Commit? (y/n) [n]: Y
$ ccccccdufvecnkcleregrvlredredbjirkbehvjitbfi
zsh: command not found: ccccccdufvecnkcleregrvlredredbjirkbehvjitbfi
$ ykpersonalize -m 5
Firmware version 3.3.0 Touch level 1285 Program sequence 1
The USB mode will be set to: 0x5
Commit? (y/n) [n]: y
$ ccccccdufvecjcenlghidbeclufjlgucvjhuutihrnnk
zsh: command not found: ccccccdufvecjcenlghidbeclufjlgucvjhuutihrnnk
$ ykpersonalize -m 85
Yubikey core error: no yubikey present
All I see reported now is "Yubikey core error: no yubikey present". When I insert the Yubikey, it blinks briefly then shuts off. It blinks periodically (once every 4 seconds or so). Touching the button does nothing.