* Since the battery still works, the loss of capacity can be chalked up to coincidence. Replacing it is [guide|133814|a moderate] job.
* Broken pixels is likely an effect of water seeping into the screen. [guide|133817|Replacing it] will be necessary.
* The Taptic Engine was likely damaged by the water. [guide|133892|Replacing it] will, again, be necessary.
* The phone randomly rebooting is likely a result of the battery being worn out. If replacing the battery doesn't work, the issue is board-level.