When I removed the CMOS/Bios battery and I connected the AC adapter the light turned on and after a while turned off. Then I removed the adapter.

I reconnected the CMOS/Bios battery and reassembled. I connected the AC adapter and nothing happened. The only thing I've heard was a noice for 1 sec, as if the hard drive started doing something...not sure what was this noise was. Then everything as before...black screen, laptop couldn't be turned on.

Unfortunately I don't have a volt meter so I can't check if the CMOS/Bios battery is ok.

Welcome to the Dell Community  @smattes 

Disconnect the AC adapter.

Remove the Main Battery.

Remove the Base Cover.

Disconnect the CMOS/BIOS Coin Cell Battery.

Turn the laptop over and hold down the Power Button for 5-10 seconds.

Then connect the AC adapter for 2-3 seconds.

Then disconnect the AC adapter connect the CMOS/Bios battery and reassemble.

Then connect the AC adapter again and it should power-on and off three times.

Let us know how things go.

Best regards,

U2

Note: If you have a Volt Meter, when the CMOS/BIOS battery is disconnected it would be a good time to test it.

It should be 2-3 volts DC.

Hi Smattes,

Check the status of the power button, Solid/ blinking, white/amber have you tried checking with a known good ac adapter or a battery if available. You can try the steps for no power using the given link https://www.dell.com/support/article/us/en/04/sln155074/how-to-troubleshoot-a-no-power-issue-on-your-dell-notebook?lang=en

This will give you a fair idea on which component might be causing the problem.

I have tried all that was suggested above, and had similar experience of seconds of turning on but the completely shut down again. The CMOS battery is fine for me, I measured 3V but my issues are not resolved at all. Really disappointed and frustrated

When I followed the outlined instructions, the computer cycled on and off for one second each time. On the third power up the entire computer started. When I re-attached the CMOS (voltage output was correct) the computer would not boot.

Removing battery and CMOS battery worked for me

Thanks

thanks lot its work for me

"Thank you so much. I removed the CMOS battery and replaced it with a new one. It turned on. Thank you again; you have been very helpful."

My dell latitude E5440, after turning it on, it won't display until I power it off, and power on again before it displays please 🙏 I need help on this 

@Grate​ i have been having this issue too for a while, any solution to your own for now.