Garage fridge electric shock when two wires switched

Greetings,
The original story was posted there:

fridge gives an electric shock after moving into garage

Since then we ended up buying a brand-new fridge.
As we found out recently it shocks also.
There is only one power outlet in the garage.
I decided to replace GFCI and that's what I found when I opened the receptacle.
A small three lamp plugin tester gives correct reading (red off, middle and right lamps are yellow) but the contactless tester gives voltage on the fridge when (!) black wire and bare brass wires are switched on the FGCI. Yes, black wire is connected to the green ground terminal and bare wire is connected to brass terminal.

If I switch the wires into correct positions: bare wire goes to green terminal and black goes to the brass terminal then the outlet pretty much doesn't work: the fridge doesn't work and the plugin tester dives open neutral (red lamp is off, middle is off, right is on).

Two questions here: could someone please explain to me what's going on here and what I am supposed to do to fix that?

And yes, if I connect the fridge to a different power outlet (not inside the garage) everything is good.

Thank you so much in advance,
Alex.

 

Fix the open neutral and connect the wires properly to the gfci.

 

Thanks for the reply!
I am not an electrician.
How to fix the open neutral?

 

Ok, I read some articles on google. I am calling for an electrician tomorrow.
Thank you!