Free Traffic Legal Advice

I wasn't looking at the time and entered a pedestrian zone (for schools), realised my error within a few meters and exited immediately. I challenged this and was told that the second I entered this zone the penalty comes in to force.

Is this correct?

If so, why is it that I can park on a yellow line, get out of my car to check the no parking times and not be fined? Isn't this the same principle or am I stupid?

I of course do not have any evidence to show that I immediately exited this zone.

Did you read the read this first sticky?

We can't help unless you post the PCN (hiding only your name and address), your challenge and their rejection.

https://www.ftla.uk/civil-penalty-charge-notices-(councils-tfl-and-so-on)/read-this-first-before-posting-your-case!-this-section-is-for-council-tfl-dartme/
Also a GSV link to the location. The sole evidence is a video, so we need to see it.