If you can still find some way of booting up the homebrew launcher then the system might be salvageable, but if not then I dunno what else could be done. I don't think there are any games with firmware versions above 10.5 on them so I don't imagine you could try a cart update. I also don't know if you can even get carts to boot in your system's current state.
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Oh wait, you can still boot into homebrew? Then you might just have a chance at fixing this thing. Follow these steps and see if you can downgrade to 9.2 again:
https://github.com/Plailect/Guide/wiki/Part-2-(9.2.0-Downgrade)