Samsung Chromebook Pro RAM No Display No Backlight Power led on EC Console

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1

I am working on one of my Samsung Chromebook Pro and am trying to troubleshoot. The chromebook has the blue power led on but no display, no backlight.

For hardware troubleshoot, I already checked the power rails and 5V, 3.3V, 1.8V and 1.2V are present.
The CPU does get hot when turned on. I soldered the EC uart TX and RX line and successfully connected through terminal to EC UART.
Unforunately, the document that I can find on how to use the EC console is extremely limited. I think the Serial EC console is very similar to ectool commands.
Anyone know how to check what is the laptop is doing and where it get stuck?
I tried to enable hcdebug to see communication between AC and EC, but it said debug mode is disabled. :frowning:

I got the following log booting the machine.

I

2

Build a coreboot rom with serial enabled then flash it and solder to the AP serial line to get boot logs

3

Is the AP serial line the AP Uart from the servoII connector?
How do I build that serial enabled coreboot? I am currently using the UEFI firmware.

4

yes

See Compiling Your Own Firmware | MrChromebox.tech