You should try a factory reset as you start the device. Use the last method on
https://wiki.mobileread.com/wiki/Kobo_Reset:_Aura_H2O.
Other than that, I don't have any ideas. There is only one Aura H2O version. The replacement is the Aura H2O Edition 2 and is quite different, and I don't think it has an internal SD card. Trying a different rating card might work, but people have tested different ratings with the different devices and it doesn't seem to matter.