Dell AC adaptor flickering green light and won't charge laptop

Solution 1:

There are two Green LED charger indicators; one on the charger itself, and one on the laptop indicating a charger is connected.

The one on the charger should be on solid as long as it is plugged in and receiving power. If that LED is blinking when it is plugged in, it means the charger is defective. Replace or borrow another to confirm.

If the charger indicator LED on the laptop is blinking (while the charger LED itself is on and plugged into the laptop properly) then most likely the power jack is bad. This happens when the charger plug repeatedly flexes the laptop's power jack during normal use - like bumping or pushing the charger plug against the laptop. The laptop power jack is relatively inexpensive (like $3) but depending on the laptop, takes significant labor to access and replace (like 30 minutes for the occasional hacker).

It is possible, but less likely to be a motherboard issue - where a section of it controls the power logic, deciding whether to get the power from the battery or charger input.