Galaxy A80 Buttons falling off

So... my mom has an A80 and some of the plastic things that you actually press to trigger the button inside started acting weird.

For example, the volume down plastic part works perfectly when you press its upper edge, but when you press its bottom edge, the upper part starts trying to escape.

And today, the power button just disappeared somewhere in her handbag, and where it's supposed to be is just a hole now.

So, is that fixable, and how hard is it? Can it be done without opening the phone, and/or are the buttons mounted to the frame so you have to move the whole guts of the phone with a new chassis?