[hostar]

I can think of two possibly solutions:

First: try to login as framework:mario and then edit passwd back. Problem is, you will not probably able to save it because of non-root. Then you can, when logged as framework, try to "su root" and try to login as root.
If it will not work, see second idea.

Second: make own OTA2 update package with kindletool, which rewrite passwd.

Better also wait for other opinions, I might be wrong.

EDIT: If you have launcher installed, maybe over launcher you can run some fixing script.