RE: Power adaptor not recognised
What is the exact system model?
When you plug in the adapter to the system, does the adapter stay firm or does it fall off easily? Is the adapter frayed? Is there any damage on the system? Could you test with another power adapter if possible?
Restart the system and press f2 key to enter BIOS - check the adapter status in BIOS with and without the adapter plugged in. Also, wiggle the adapter cable at the end and see if the status changes in BIOS at any point.
Update the BIOS - enter the service tag and download the BIOS, update and restart the machine and check.
Restart the system and press f12 key on startup - choose diagnostics. Let it run the diags and if you encounter any errors - make a note of the complete error and report the same to us. These are onboard diagnostics and they might possible pick some error if the hardware is not functional.
Also, please click my DELL-username and write me a private message with the service tag and your Name for case records.
Let us know if you have any other queries.