Minimal water damage resulting in display not powering

While camping, my iphone6 was in my pocket and my jeans got slightly wet, nothing at all i was concerned about. Phone was in a case and I removed it and it looked fine so I continued on. Few hours later the Power Button failed to work so I continued using the phone with assistive touch thinking that it was a faulty button. Next day the screen fails to turn on. Siri, home button, speakers all still worked. Later in the day all functionality stopped working. However, when connecting to itunes, it'll remove pictures from my phone and itunes recognizes my phone and asks me to unlock it to continue.

Made an Apple apt today. He ran diagnostics and all was fine, so he then said the motherboard was bad and suggested I replace the phone. I questioned why the phone still connects to itunes, thinking it was a bad display. He agreed. They took it apart to attempt a screen replacement only to return the phone to me telling me that the water damage indicator was tripped so they will not attempt to repair the phone. I'm holding out for the new iphone however would like to resurrect this one.

What to try?