My phone got submerged in water a while ago and wouldn't turn on for months. It started turning on when I plugged in a charger cable, but it won't boot beyond the initial power on screen. I have managed to access recovery and download mode. The battery swelled up and forced the rear panel of the phone off, so I have disconnected the battery. I have removed the main board and cleaned it, as well as other parts, with isopropyl alcohol, to no avail. Is this just a case of the phone needing a new battery, or is there something else that I need to do?