There is no way to tell whether a Power Bank is damaged...

When a power-bank is dropped into liquid, it gets damaged. But there seems to be neither a way to repair it, nor a way to check it for damage (except dropping it into liquid and getting it damaged some more). That seems to be a rather serious oversight.

Incidentally, we do not have a rechargeable power-bank that is made from renewable materials. I would consider that also a design defect.