The micro USB port on older Pro Micro controllers is the single most common failure point in a custom keyboard. It is held on by a few small pads, and after a few hundred cable insertions it starts to lift. Once it does, the keyboard goes dead mid-sentence.
This service replaces the controller with a USB-C version. The connector is mechanically stronger, the cable goes in either way round, and you stop treating your own keyboard carefully.
Shipping both ways is on your side.
