My name is Shrikanth and I work for the Social Media and Community Team at Dell. If the AC adapter light goes off when you connect it to your computer then it might be an issue with the DC charging port or a system board failure. Let me know if your system is in warranty to proceed further.
My computer (Dell Inspiron) is having the same problem (the green adapter light goes off when i plug the cord into my computer). My computer has a 1 year warranty. Which next step(s) should I take?
Please would you NOT listen to Shrikanth, I have had the same issue too, and I can, to this date, replicate the fault, it's the power supply main unit, all you do is replace it with a third party or an original one and you're good to go. I have posted this answer on another thread too, but I thought I'd share it too on here as the answer from the 'tech' is wrong! It has nothing to do with the motherboard.