ThinkPad X1 Carbon 6th Gen (20KH) does not turn on anymore

[npcap9000]

I have a X1C6 that stopped turning on. It may have had an unexpected shutdown due to low battery SoC prior to the incidence.

This is the troubleshooting I've done so far:

• When I press the power button, the power light on the left of the device flashes very briefly once, but inconsistently.
• When attached to a power adapter, the power LEDs at the power button and the side blinks three times and then indicates charging/full charge with an organge or white light.
• The BIOS chip has power and clock.
• Continuity check on the flex cable pins shows the power button works.
• Detaching other components does not help.
• The usual tricks such as pressing the reset button or detaching/re-attaching the battery do not help.

[RealBlackStuff]

If you can still get into the BIOS, try this.
To disable the built-in battery, do the following:
1. Restart your computer. When the logo screen is displayed, immediately press F1 to enter ThinkPad Setup.
2. Select Config ➙ Power. The Power submenu is displayed.
3. Select Disable built-in battery and press Enter.
4. Select Yes in the Setup Confirmation window. The built-in battery is disabled and the computer turns off automatically.

Now disconnect the charger and press/hold down the Power button for ~20 seconds.
Reconnect charger, try to boot.

[npcap9000]

Unfortunately, the screen stays black entirely.

[Neil]

[*]The BIOS chip has power and clock.

How did you determine the above to be the case if the screen stays black?

[npcap9000]

[*]The BIOS chip has power and clock.

How did you determine the above to be the case if the screen stays black?

I had someone measure it.

[frankp01]

Do you get audible error tones at startup? I have a 7th Gen that's had its LCD display replaced twice, and it's doing the same thing again. It appears to be not turning on. An external display is getting an HDMI signal, but the laptop boots to a black LCD screen, and generates dijsplay error 288 (translated vai the Lenovo Diagnostics app).

[RealBlackStuff]

The HMM says this about Error 288:
- either reseat the LCD-cable at both ends
- or replace the motherboard

I suggest to also check all the fuses around the mobo's LCD-connector for Continuity.