If the brake pads are worn, some measures must be taken before you can start working on the brake system.
The electric parking brake is very sensitive to any small voltage fluctuation, so that (if possible) always a battery charger should be connected to ensure a sufficient and constant voltage.
In addition, it is essential to ensure that the brake system works correctly and no fault codes are present.
Of course, you can try to diagnose your model with Carly Full Version to check, if there are any Fault Codes in the brake system.
In Order to be able to work on the brake system, the vehicle has to be on a lift. The Ignition should be turned on, and the electric parking brake has to be released.