US customs won't care if they find new electronics, so they're no problem (they are annoying, with the suitcase thing at port-of-entry, but no problem). As for German customs, I don't know, but: do the initial leave out of Germany over the road where there's checks only in theory and leave from an airport not too far over the border. You can probably get a cheaper flight in the process (e.g. Fly from Basel)

The Germans look for electronics, the Americans look in the electronics and what’s on them.

Fly back through Geneva, and take some basic precautions, such as not taking the box. Done/done.