Hi,
Do a hard reset first, remove the battery again and unplug the AC adapter then press and hold the power button for 20 seconds. Put everything back together and see if it will load normally. If it doesn't, reseat the RAM as well, take them off and put them back in making sure that they are seated properly into each slot. Lastly, plug the AC adapter in without the battery and check if it would make any difference. If all these steps won't work last thing you'll need to to is to reset BIOS to default by removing the CMOS battery for couple of seconds then put it back in and see if your laptop will boot up. Worse case is you'll need to contact the manufacturer for a repair if it's still under the factory warranty.