While looking at \Windows\system32\oobe\ files I had a quick check what FirstLogonAnim.exe does and discovered that on top of accepting the following command line arguments:

• /zdp (for Zero Day Package)
• /oobe
• /oobetransition
• /existinguser
• /explorer

it can be run with /RunFirstLogonAnim as a first argument and in such case will launch the ‘Windows installation’ animation. If both /RunFirstLogonAnim and /explorer are present in the command line, you won’t be able to close the animation.