Dell Inspiron n5110 3 and 4 beep problem.?

i couple weeks ago I spilled beer on the laptop...it worked for a day or so and the the screen went white. I restarted it and it started beeping 3 times over and over. So I searched the Internet and it said the motherboard was bad. So I took the mother board out and was gonna order a new one the next day but never did because something came up and I ran out of money. So it sat apart for a couple weeks the memory sticks were in a plastic ziploc bag and everything was kept in order....so today I was bored and decided to just put the laptop back together. I got it together just fine and when I tried to boot it it started beeping 4 times over and over which to my knowledge indicates a memory failure. I tried taking the ram sticks out and blowing on them and reseating them real good and everything but it still does it....so can anyone tell me how to test each of the sticks to find out which is the bad one one or is there something else I should be looking for? One stick is a 2 gb and one is a 4 gb. Also is this something I can get at like office max or staples or do I have to order them off the internet? Any information on how to proceed from this point would be much appreciated.