Compaq Presario CQ61-420US Not Booting/blank Screen?

I have a Compaq Presario CQ61-420US Laptop, it will be a year old at the end of April 2011. It has Windows 7 Home Premium 64-bit OS. Never had a problem with it till now. I am planning on doing a memory upgrade (currently has 3.0 GB DDR2 PC6400 in 2 slots (1gb + 2gb), ordered a 2.0 GB chip to bring it up to 4.0 GB total memory)Anyway I wanted to make sure I could do the swap myself so I unplugged the power cord, took out the battery, unscrewed the panel on the bottom of the laptop case, found the memory chips, took out both chips very carefully, undoing the tabs holding the chips in, took them out, inspected them, put them back in the way I took them out, making sure the tabs on the chips were lined up, maing sure the contacts were making contact. Put everything back together, ordered the new 2GB memory chip.

Today I went to power up the laptop, battery in and power cord plugged in and everything lit up like normal except the screen never came on, the power button stayed lit, the network status light stayed on, the power indicator was lit, two white lights were flashing at the same time every 5 seconds though, which is abnormal, one at the top right of the keyboard which I believe is the Num-lock light and one on the far left of the keyboard which I believe is the Caps-Lock light. And thats it, nothing ever happens it never turns on (blank screen) even after 20 min's. SO I held the power button down till it powered off. Unplugged the cord, took out the battery, held the power button down for 30 seconds, put the battery back in and tried powering up again, still the same thing.