I hesitate to even say this because it is not the most honest thing to do. I hope you don't think bad of me when I tell you this, I really am a good honest person. I just think we all work way to hard for our money to go through all of this to get what we pay for,a good product. I know it s not the stores fault you may have pruchased the lemon, but it would be nice if they would be more helpful. Ok, if the store still has the same monitor (assuming you would not mind to have another one) buy a new one, put the broken one in the new box w/ the new receipt and return it.
I know it sounds shady, but I have had to do it. My husband got me a new coffee pot or Christmas and before it was a month old it was not workng. Well you know men, he did not save the receipt. I called the store where he purchased it and they said w/o a box or a receipt they could not take it back. I had to prove it was purchased at that store. I was kind torn because I did not really want the same coffee pot, but I did not want to be stuck w/ a broken $60 coffee pot and out another $60 for a new one. Well I did it, I went to the store and purchased the exact same coffee pot, put the old one in the box (i did clean it up first)and returned it w/o any prolem. I did tell them it did not work so they wold not sell it to anyone (how honest, lol).
Well anyway it is just an idea. Since it is 6mo old they may not even have it anymore, and you may just want differant one all together.
I just thought I would share that idea even though it is not very honest. I really am a good honest person. Maybe calling fisher price is the better way to go, but if you don't get results or it becomes more work then its worth it is a quick fix.