Ok so I'm all about reading, following tutorials and figuring it out yourself. But I'm really stuck and I'm obviously doing something wrong, I just don't know what. I hope you can point me into the right direction.

Device: TomTom XL with IQ Routes
Bootloader (according to the file on the device: 5.5279
Navcore: Navcore_9.540_SE
Map: United_States_1015_9160

So I've extracted the downloaded files, as mentioned above, and run FastActivate. Patching Navcore tells me it's already patched. When I patch a map I get following:



This makes me believe all is set and ready to go. Except, every time I start the device it runs through the setup wizard and ends with the message 'No maps found!'.
What am I doing wrong?!

Usually the 'No maps found' error is because the navcore isn't patched (FA option 3) but you say that you've done that...

So double check the map folder itself, the map should be contained in it's own folder called 'United_States_1015_9160' and be placed in the root of the device.

Note that the name of the map folder shouldn't have any spaces/special characters and shouldn't be a folder within a folder...just a United_States_1015_9160 folder in the root

Yeah, mind that the actual map folder "map name" is not nested in a "map name" folder.
So if your TT is connected to e: make sure your map files are in e:\map name\

Device settings including the folder path to the current map are defined in ttgo.bif.

OP, you probably forgot to delete ttgo.bif when you copied the new map folder onto the tomtom root drive. After a restart, the ttgo.bif file gets regenerated with the updated map folder path.