iPhone Xs Max keep restart every 3-4 minutes. After water damaged

Hi this case is not my first repair job regarding this issue. I received an IPhone Xs Max keep restart after water damaged. The things that I already do is…

1. Water Damaged cleaning using isopropyl alcohol
2. Disconnect all the connection except LCD & Battery. (using new LCD & Battery) The result still remain the same issue
3. Lastly I change a new motherboard and disconnect all the connection except LCD & Battery. (Once again the LCD & Battery I bought a new one) The result still the same

Ive read a lot of information in the internet, some people said it is because of the wireless charger. But I already disconnect the wireless charger and still giving the same result.

So my question is, does this because of the housing itself ? Or is it because of the motherboard ?