Hello Tomek.
I will post the clear video for you later.
Maybe you have to use knife unrip the protection pad on both of two side and then disassemable it .
How to adjust the orientation of your GT16 as follow:
Firstly you turn off the EUC, and then press the button, a few times after a short long beeping , shut down,
After that you turn it on ,you will find it's ok .