Why none of any sensors are working?

My phone got a splash of sea water on the upper portion just for few seconds. When i checked my phone none of any sensors were working ( checked on CPU-Z app). No rotation, No brightness adjustment, No mic, No speakers, No flash, No front/rear camera.

Only GPS, WiFi & Phone Networks, Fingerprint, Display, Touch, Charging Port were working fine. And after 2/3 days Both Cameras & Flash works perfectly fine.

To fix sensors issue i visited service centre. They told me change the Motherboard which would cost me 200$ approx.

Is it fine to do so ??