Not too bad to remove it, at least on my F30. Pull the trim up then unplug the cable and it’s 3 screws to undo the entire controller.
When I spilt Pepsi Max all over my Mondeo’s heated seat controls it started doing some weird things like unresponsive buttons and flickering lights. I sprayed a whole load of contact cleaner into it which did at least stop it sticking and made the passenger side work again. In your situation I’d use some contact cleaner, it won’t harm the electronics and it evaporates quickly so get some and spray away
Worst case is you’ll need a new iDrive controller but a used one from eBay isn't too expensive really.