Rice trick is that we've all been tricked into thinking rice helps with water damage. It doesn't :(
This is going to be a board repair and it is likely cheaper to just replace a 4th gen touch rather than investing in parts that may not solve the problem. You'll have to be handy with a soldering iron to even get the board out to clean the back side of it.
If you're up for it, post back and we can help you. Step one: follow a guide to open this sucker up by removing the front screen and unscrewing the metal shield. Desolder the battery and the power flex to remove the board. Report back!