Visited on April 3rd and charged without any issue.
I expected to see signs for the parking with Migros logo, but all the parking signs actually say "P Bläuacker". The entrance is inside the underpass under the train. You can arrive from either the east or west. At the bottom of the underpass there's a fork in the road and you can enter the Migros parking.
There are no gates, it's a parking meter. I'm not sure how they can close the parking, but there are signs saying it closes 30 minutes after the store. There are 2 hours of free parking.
The entrance level is -2 and that's where the chargers are, though there are no signs. There is another level of parking at -3 which I didn't visit. Level -1 is the store.
It was challenging to take pictures because there was a constant flow of traffic. But no ICEd spots.