In order to release the electronic handbrake, by pressing down the handbrake switch, you must have yr foot on the brake pedal.
In my pré-facelift A5, I did change that, so I could release the handbrake all the time.
but this can be dangerous, if the switch is pressed accidentally.

1. Select module 53 - Parking brake
2. Select Security Access - 16 and enter the code from the popup screen (25194 - pré-facelift / 78713 - facelift)
3. [Adaptation - 10] --> channel 04 – Click on ‘Read’,
4. Change the value into “0” ( = inactive)

 

It don't work if I have my foot on the brake pedal or seatbelt on.

I'll give this a try, thanks

 

It don't work if I have my foot on the brake pedal or seatbelt on.

it will only work if the ignition is ON, or the engine is running.

 

I tried all that and it don't work

Also, my 53 - Parking brake module channel has many options but I do have "Manual release"

I set Manual release with button and brake pedal depressed and it's not working

See attached image