Board Repair - No Backlight, display is working

Hello, i'm getting to a no end and i will try to add as much information as i can.

I have an iPhone 5S to repair, the start problem was no touch. The board was water damage sticker in red so i have clean the board in a ultrasonic cleaner. After that as LCD replacement didn't help i've reflow the touch IC U12, which solve the touch problem, but after a short time backlight gone [I never connect stuff with battery in], it have image, touch continue to work as the iPhone. So i start to test stuff, all filters, inductor, caps etc are good, i have two dead boards that i use to gather the components, and i have tried to swap the L3, D1, C131, U23, U3. The result is the same, phone work but no backlight... The Connectors are good, LCD is good so i reach a end without a solution.

C329: 6V

C52: 5V

C330: 5V

C103_RF: 5V

C369: 0V

C131: 4.2V (VIN) (Yes i know it should be 16V but i can't find why)

PP_LCM_BL_CAT1_CONN: 0.6V +/-

PP_LCM_BL_CAT2_CONN: 3.2V +/-

PP_LCM_BL_ANODE_CONN: I don't renember the value but is not normal...

Again FL's seens OK and none is open, voltage reach there.

May i be out of luck and the U23 i took from other boards are damaged too?

Any recommendations?