puttelino,
start a new thread.
This has become a thread hijack.
The original thread was a simple "Hey, here is how to use this i2c lcd backpack".
It has now drifted into working through some sort of software/wiring/hardware issues.
I recommend that you start a new thread
and post photos of your board and show the current code you are running
so we can then proceed helping you bring up your board.
--- bill