no backlight, keeps rebooting after water damage, all other works

I fall into water with iphone, i turned it off dired, wiped inside did all the steps you would do(put in rice for a week).

After pluging it into charger it booted screen was working, typed pin code, pushed few icons around, then pushed power/sleep button and that was last time I have seen display working.

I could ssh into it, touch screen works too, when in charger I can unlock it by swiping on screen turn ipod, etc but screen stays totally black. It is also keeps rebooting every few minutes.

After browsing internet I found that 3G/S 6R8 coil is to blame after water damage but i guess ipone 4 doesnt have one? What can I check or replace ? Somone said here that replacing whole scren rather wont help.

Battery is probably dead thats kinda obvious but what about reboots? some shortcut or is that connected with screen issue?