In some laptops, a completely dead battery will prevent the laptop from running, even with the AC adapter plugged in. What is strange is that you're getting that LCD reading. But that LCD reading is obviously wrong because it doesn't change. The LCD probably gets its power from the internal battery (so it can always show a reading), not from the main battery--which itself is charged by the AC adapter. So: Your main battery is dead, preventing any power flow from the AC adapter through it to the power supply and causing the LCD to have a strange reading, or....
Your power supply is dead, but that doesn't explain the unchanging LCD reading, or....
There is a disconnect between the AC adapter, battery, and power supply.
My money is on the battery. A test: if you can (could before, actually) run the laptop without the battery even being installed, then it's not necessarily the battery. Again, some laptops can run straight from the AC adapter, others have to have the main battery installed and drawing juice from the AC adapter.
If you have a local repair shop that will work on laptops--and if you don't want to mess with NEC, of course--then have them take a look at the whole power management system. They should be able to find the problem, and possibly even repair it, if necessary.