Assuming the EPB successfully deployed, it would require a positive command from the associated ECU to retract it - without the application of 12V (or mechanical force), the motor cannot move (it would require a massive effort to reverse it against its internal gearing). The motor can be (slowly) unwound through the application of a suitable tool.
I noted the other day, that I had to operate the Tucson's EPB switch THREE times, before it actually did anything
. Each time, I got a nice positive 'click' from the switch, but no deployment of the EPB. (My 'other-half' reckons I don't hold the switch up long enough - she may well be right!).Of course, the car is setup to automatically deploy the EPB, but that doesn't always happen either- no doubt it is for some justifiable, algorithmic reason - but the car doesn't see fit to inform me! (This car can talk when it wants to. It also has several large display screens... )
The most likely scenario, is that the EPB simply wasn't deployed. I have certainly managed to do that in the past, though thankfully, without any ill effects
Just an after-thought: Did the Door Bell camera manage to capture the sound of the EPB deploying
The sound is quite distinctive.
