Macbook pro retina a1398 no picture or backlight

[phantom1]

Hello everyone in help with a macbook pro retina 15.4 a1398 emc 2909 no picture no light.
Cam in for battery and spk, screen was working
After replacement of said parts no picture or light. I do have hdmi out with 50v on caps. But with out hdmi just 12v on caps trying to narrow it down thanks for any help

[mon2]

Re: Macbook pro retina a1398 no picture or backlight

Double check the area that were serviced.

Being battery related, do check the voltage to ground of the SMBUS SCL and SDA pins on the battery connector.

If the voltage reading is not ~3v on each pin, then the TV's esd diode is a suspect. Sometimes, the ESD protection diodes will get zapped during the manhandling of the logic board. This zapped diode will then shunt the signals used for communication.