It looks to be gone. If stuck on boot-loop, its usually a bigger issue. Try getting a splash proof coated tablet next time for kids, because kids are kids!
Lenovo Tab3 7 inch is a newly launched budget tab with nano coating to prevent accidental spills, but there would be many other options too.
Many laptops come with some liquid resistance, atleast on the keyboard, so that's why it was saved, otherwise motherboard gets liquid damage pretty easily and makes a dent on pocket sometimes.