Can anyone tell me what the issue can be, any guess

I have an iPhone 14 Plus that was water damaged. I cleaned the motherboard properly using isopropyl alcohol and then lightly dried it with a heat gun just enough to evaporate the alcohol. After that, I reassembled the phone. I cleaned all components the same way except for the charging port assembly. I only cleaned the charging port from the outside and did not remove or clean the flex cable.

I also replaced the battery with another one to rule out any battery-related issue.

After putting everything back together, the issue still persists. When the phone is unplugged and I try to turn it on, it makes a small “cling” sound and then goes directly into DFU mode. It keeps repeating this behavior every time I try to power it on.

When I connect the phone to a laptop while it’s in DFU mode and attempt to restore it using iTunes, the restore process starts but freezes halfway through. The screen stays stuck for a long time and does not complete. I repeated the process multiple times with the same result. I also tried restoring using 3uTools, but it behaves the same way, the restore begins and then gets stuck halfway.