Accidentally left an iPhone 3Gs out in a rain storm. After leaving in a bag of rice for a week the phone worked fine except for random reboots.
I used the home tech toolkit and detailing brush to open and clean the contacts on the phone. Lucked out that internally things were okay except for some crud between the battery and logic board. Cleaned that up, things are working great!
Removing the glass from the 3Gs took more force than I expected. I wish there was a kit that contained cleaning supplies like some iso. alcohol, swabs, and a mini tray for the screws.