I own an ancient Android phone (four years is a long time in the tech world) that I keep trying to destroy. In December I left it on the roof of the car and drove away. A few blocks later, it fell off the car and was run over by another car. A replacement from eBay arrived a week later. Then a couple of weeks ago, this new phone fell into a water hazard. I retrieved it quickly, but it crashed and got stuck in the boot loader, as if the operating system had disappeared. Removing the battery (and, obviously, the SIM card and SD card) and letting the phone dry out for a week didn’t help much. Sometimes it would boot, but would immediately crash into the boot loader again. The side buttons were also behaving badly, as if they were being pushed by a chimp on speed.
I finally took the advice of this post and tried the alcohol remedy. This involved disassembling the phone and soaking the logic boards for a few hours in 99% isopropyl alcohol. (It is a Very Bad Idea to soak the entire phone in alcohol, because the display can be damaged.) After removing the boards from their bath, I let them dry for a day and then reassembled the phone. Amazingly, the phone now works perfectly and has been running for a couple of days without a crash or other hitch. I believe that the alcohol bath did its trick by removing all water that had remained in the phone, and by cleaning away impurities in the water.