PM sent with the link. Have a look at
Memory Upgrade Mod Guide for instructions on writing the image to the card.
I don't expect that you will be able to recover from this as the water has probably damaged other parts of the device. At the least, you should disconnect the battery and let everything dry properly. Some people recommend putting the devices in rice to absorb the water. The times I've needed to do this (apple juice spilt on a laptop), I put it in a nice warm dry spot for a couple of days.
If you can't get it going, I recommend a Kobo Aura H2O. Dropping one of those in the bath won't be a problem. And a nice bunch of flowers to cheer her up