Nintendo switch no short charges fine battery full but no boot no sound

As the title says I have 2 switches showing the same symptom. One switch one lite

After quick investigation I found no short on usb c power of or video chip.

Initially the batteries was flat, after leaving it a while to charge they got full just fine. While charging the battery icon was not shown on screen. Using usb meter gave usual reading that is 15@0.1, 15v@0.5amp during early and middle of charging cycle respectively

To check if the battery is charged or not I teardown the unit and directly probe battery terminal which gives 4.17 volt more or less .

Pressing power button doesn’t give any response, no sound or picture. Long pressing do nothing either

I am really confounded and hope gurus and masters here could point out possible fix

Thank you

It seem the charging capability is ok. There are a few option

  1. Check if it is in RCM mode.
  2. check the resistance on the pmic rail
  3. take out the p13usb and see if it boots.
  4. Check if you get the enable signal for the LCD to start (1.8v) I believe.

Turns out the backlight has died when I shine with flashlight I can confirm lcd shows homescreen just fine. Any idea which circuit powers the backlight ?

The backlight IC is a tiny little 9 ball BGA chip on the other side of the board from the power connector. the chip is a TPS61163A, you can get them easily enough on Aliexpress.