You can reset your PIN on a 4000 box without using Libby and opening your box
1. Assuming you've forgotten the PIN you put any old PIN in 5 times so that the box reports that the PIN is locked.
2. Go to the Menu option where you would unlock the PIN, and put in any old PIN (it shall probably tell you invalid pin entered).
3. Then reboot the box and go into Engineers menu (holding down the up and down arrow buttons whilst the box is being booted up).
4. You should now find that you can actually move down to the PIN option on the 1st page and reset the PIN using the buttons of the box.