You can make it do a bunch of stuff if you get creative with shortcuts.
My action button silences the media volume (and the phone just in case) and then vibrates the phone to tell me it has done this IF the phone is in a face-down orientation. Otherwise it toggles the flashlight on or off.
I’ve seen people with dozens of actions tied to the button depending on focus mode, orientation, time of day, location, all sorts of stuff.
Try cleaning out the USB-C port. Lint gets compacted in there and it can prevent the plug from seating correctly. Most charging problems I’ve had were resolved by scraping the lint out of the port, with a plastic floss pick thing or an unbent staple. Careful not to damage the contacts though.