Back from the dead!?
I dug the H320 "toilet diver" out of the junk drawer today, on a whim. The unit powered on (with the battery removed, on AC) and Rockbox started! No more hissing and whining noises coming from the chipboard. Looks like the battery was shorted and the motherboard was still wet after 24 hours and various attempts to remove the moisture. Thanks for the suggestions though! I guess good old evaporation (and patience) was the final solution.
Thanks everybody for the suggestions and support!
EDIT: The controls are scrambled (in Rockbox and iRiver firmware, with or without using a remote), and I noticed some corrosion spots on the mainboard. Meh.
Edited by slag - 8/25/10 at 7:35pm