This could be several things but the first thing I would do is replace the DC IN port.

it sounds like one of three things:

1. Battery itself no longer functions

2. Laptop Charger has inadequate amperage

3. The motherboard is defective (most likely).

If you have another battery, or a friend with the same battery, you can try that first (and someone else's laptop charger).

If the problem is the motherboard, you can try to have it repaired but I don't trust many companies to do this kind of work. I outsource my motherboard jobs to a company called Laptop Rescue (http://www.laptoprescue.com/laptop-repai...). Coincidentally, they also sell laptop chargers in case that's the problem. Hopefully it's just a charger or battery issue and not a motherboard.