I did the same thing you did.. Wazapp.. faster N9 new version.. Even rebooted to make sure everything was in order. So far it's working fine, thank God. But yeah, when you "update" apps.. make sure your battery is full or that you're connected to a charger. The phone has a tendency to keep going "sorry, not enough battery for doing that, plug yo charger, dude" so it must have done that like half way through installation of fasterN9 or wazapp or something.

Reflashing should bring it back new.. Although I hope you backed up everything before doing that