Water damage, not booting up but flashlight is on

How exactly have you cleaned the logic board? I usually advocate for fully removing the board and scrubbing down with IPA. However, the SE is literally entirely covered in shields so it's very difficult to do a proper cleaning with removing the shields.

A professional repair shop that does water damage repair may be able to recover your phone or the data because they have access to pro-level ultrasonic baths and specialized cleaners, the tools to remove the shields as well as the skills to troubleshoot your board. Many shops have a no fix/no fee policy so you don't have to spend money to find out if the phone is fixable or not.