If the AC adapter is overloaded it appears from reading the text below that the Green light will go out...
Text found at
http://en.community.dell.com/support-forums/laptop/f/3518/p/17837320/17967881.aspx
OK, I'll give this a try. You need to isolate this to: (A) bad AC adapter, (B) bad battery, or (C) bad laptop. I assume you don't have 2nd battery or AC adapter to try. There are "protection" circuits built into these items to prevent thermal/current overloads which may be shutting things down.
Step 1: Disconnect everything from everything, including AC adapter from wall plug and wait a few minutes.
Step 2: Connect just the AC adapter to the wall plug (do not connect to laptop). Verify that the green light in the AC adapter is on.
Step 3: Remove battery from laptop. Plug AC adapter into laptop. Does the laptop boot and run?? If NOT, is the green light still lit on the A/C adapter?? If laptop boots and runs, this implies that laptop and adapter are OK (almost). If laptop doesn't boot and AC adapters green lit is off, then it could be either item. The laptop may be overloading the AC adapter (which shuts off) or the AC adapter may be bad, BUT since the laptop runs on battery alone, try another AC adapter first.
Step 4: Remove AC adapter from laptop and install your battery, Does laptop boot and run?? Does power meter recognize battery and give charge level?? If NOT, suspect battery first and laptop 2nd, especially if Step 3 was successful.... If laptop works with battery, power laptop off.
Step 5: Disconnect AC adapter from wall and connect to laptop, but keep laptop powered off. Plug AC adapter into wall and verify still have green light on AC adapter. If green light is off, AC adapter has shut down due to excessive load from battery/laptop or maybe adapter is going bad and is unable to supply sufficient current. If Step 3 was successful (i.e. you can run laptop on AC adapter without battery installed, suspect a bad battery pack). Remember, just because a battery supplies power to a laptop doesn't mean its cells aren't going bad and overloading the AC adapter.
Step 6: With AC/Battery/Laptop all connected, BUT laptop turned off, verify that charging light on laptop is on. It may flash as the battery reaches a full charge. Once fully charged (hours), the light should go off. Does the battery fully charge???
Step 7: If battery fully charges, try turning on the laptop and see if it boots... If so, I suspect that your AC adpater is unable to simultaneously charge the battery and power the laptop without a thermal/over-current shutdown (AC adapter shuts down and green light on adapter is OFF).
Hope this helps and good luck....
Edit: Not sure about Dell, but batteries are good for 300 to 500 charge cycles... How old is your battery?? If you do a lot of off AC Adpater work, followed by recharge, etc. you may have reached end-of-life on battery. If you have to shot-gun, try battery first (if you're wrong, you have a useful spare battery), AC adapter second (spare AC adapter is sometimes handy), and laptop last (spare motherboard is $$$$).
Peccavi
December 2010