Water damage, backlight not working!

Driving at night with my wife, I decided to charge my iPhone. I connect the iPhone to the car charger and place the iPhone on the cup holders of the car. After 2 or 3 minutes I grab my iPhone and felt it wet! My wife had left a small McDonald's water cup and the iPhone was in it upside down. The screen started to come on and off until it when off completely.

After I got home I turned off the iPhone (I think, the screen was black), and left it in a bag of rice over night. Didn't work. Then I left it in the bag of rice for 24 hours. Didn't work!

My friend changed the LCD screen and the Apple logo light up for about a second and the screen turned black again.

It turns out the backlight is not working. I let the battery die and let the iPhone sit for like a month and a half. I had given up on it.

Then, I decided to connect it to the charger and the low (red) battery icon turns on! The screen was working! I was pressing the home button every time the screen dimmed to make sure it was still working and it was. Then the phone turned on and the backlight didn't work again!

I turned it off and on and the Apple icon came up for a second and then the screen turned black again!

Is the backlight the problem or not? Why was the backlight on while the low battery icon was on it and when the iPhone turned on the backlight stopped working?

What's really wrong with my iPhone?

Thank you,

JEMF