Catalin's dashboard

hi,
I took my macbook pro to a authorized service because wasn't starting at all, the chinese told me that's the battery fault and I have to change it, also the main board, he replaced the mainboard but not the battery so I went to buy a new one, I've put the new battery but now near the clock on right corner my battery is marked with an X as it's not there, if I don't keep it pluged in it won't start, the led on charger is green for a few moments then is turning off leaving me with the computer on but without charging. Anyway now is not taking dvds either so I'm starting to hate mac book.

any ideas?