Ok, I have some questions, In the past its works fine?
Try this, take apart the battery, connect the new AC adapter, check if the panel led is on (thats indicated that the AC adapter is correct and recieving power), and try to power on.
If the led panel its not on, the problem is the AC adapter is not working or the power secton in the motherboard could be damage.
Try another thing, if its possible removed the Ram dimms, and trun on. If the computer starts working and display there is no ram, the problem is the dimms chips are damage, try installing the original dimm, and do the same, if not, try the another dimm if there were 2. If still not working. remove the hard drive, do the same. If still not working, the problem is the power section, could be blowed.
If you still have warranty go the an autorized service office, to fixed. Good luck., replay if the problem were fixed.