Okay, but what's in the module itself?

Probably magic.

And glue. The front and back module covers are very well glued in place.

Plasticgate 2016 update: That small front cover is plastic, but the rear one is certainly fancy aluminum.

Picking apart the module reveals a few screws, some glue, and a surprising amount of goodies awaiting perusal.

In addition to making USB port replacements easier than ever, the tiny battery module also contains a speaker, some antennas, and a lot of spring contacts.