iPhone 6 Plus water damage, front/rear camera/flashlight not working

So I was on vacation last week when I decided to test out my waterproof bag I had laying around in the pool.

Long story short, the bag was indeed not so waterproof after-all as it indeed leaked quite a bit. 😢

The phone was still on when I pulled it out of the case but the screen went black and it was done.
Dried it off at the hotel yet for the next two days it was completely unresponsive.

I took it home and did the rice method for two days. The phone finally turned on but I was met with the red screen of death after the apple logo went away.

Phone did not respond via USB, even in DFU mode.

I decided to put it in rice for 3 more days.

The phone is now fully functional despite a small water stain and a flickering screen from time to time.

Bluetooth, wifi, mic, speaker, everything works. Except for the cameras and the flashlight.

I have tried to open the camera in the default app as well as third party, but it just gives me a black screen.

Flipping on the flashlight via the swipe menu does nothing. The button activates and deactivates a second later.

It appears to me that the software is glitching as this happens when I try to switch flash on:

My question is, what is the next step to repair this issue?

I have thought about updating to the newest firmware but I have noticed people without any hardware damage are experiencing the same issue:

iPhone 5 camera not working after 8.3 update

I have yet to open the phone up, wondering if that is what I should attempt to due? (Check for corrosion / clean with alcohol)
Or should I just attempt a update/restore (even though newest firmware is having similar issues)

Any advice would be much appreciated 🙂