It doesn't need to be done incrementally. Your original NDS file should be good enough which you overwrite onto the new download. You do it on slot1, which is the map slot.
Any Mac OS involved ?. That can lead to issues. CleanMyDrive is run on the SD card once the images is on it. Saying that there are more issues with the mib2 high and people not using CleanMyDrive than on the standard unit, but quess the rubbish that Mac's put on files they could upset the unit.
There was a reported issue once on one release of the SD card where it was released without Mapcare being active. In that case you used the version on the update rather than the original... that was on a Spanish board I read that. Very specific to the year of release.
Normally any release before the release you are on will work. I was sending someone back to the year dot one on the
resource section of lost and found. Tab top left. That didnt work for them but a later release did. Thats on the thread. Ofcourse you dont know whether it was that or a fumbled process on the one on the thread. Normally the year dot solution for the NDS file works.
The Seat year dot of Mib2 Standard on Seat is this:
That NDS file should / will work with all subsequent releases all things being equal, if not we have to find one just before yours. I'd try that first if it's not a Mac issue. Then I'll go thru the thread when the fix all solution didn't work.
You find out your original release of the SD card you are on by what is printed on it. If you put a photo up that will clear that up whether 1410 or not.
I reckon the issue with this one was a Windows 11 format.
I just tried updating my maps on my 2018
Cupra 300 w/ Virtual Cockpit. I followed the steps to update maps, backed up the original SD Card, replaced the new OVERALL.NDS with my backed up one and then when I put it back in the slot, it comes up with the "Navigation database not available", and...
www.seatcupra.net
Never reformat the card, just delete what is on it. Windows 11 format on that managed to hash the card. Recent reports show that formatting these cards rather than a simple delete damages them. In that instance, you need to buy a new card as per the conversation. That's another thing to check.