Welcome to the forums
Does the hand move slightly as if its loose? It could of been caused by the sharp, fast flyback when resetting if the hand tube is not firmly on its pinion. The only way to correct this is to remove movement, then remove hand, and refit hand in the correct position. This is assuming you have a 7750 movement in there and not a quartz?
Would be nice if you shared the actual issue you repaired mate?
I came across a similar issue, and it was the calendar gear pinion has broken of the main plate.
It should accept genuine ETA parts if its the super clone movement of TC's. How have you decided its the date jumper? Are you comfortable in working with watch movements? Where are you located Max?
Good advice above. Its only when refitting the hands you need to worry about the midnight setting/hands.
The button you mention is on the underside of this part of the keyless..
My wife has had similar with our paypal account. She had to supply a photocopy of her passport, and a copy of an electricity bill to prove address. This was to increase incomings limit which had been reached.