@ameliaw not sure where you reside but do not worry about the warranty stickers. Not even sure if your laptop is still covered under warranty :-) Read about the legality and the OEM's thinking with those stickers, on here https://www.ifixit.com/News/10016/warranty-void-if-removed-stickers Best sentence in that article is right here "So go ahead, stop living in fear of warranties! Every sticker you peel off is an opportunity to stick it to the man."
To work on your laptop properly, use the [document|40343] that way you know you are doing the right things.
***Repair is War on Entropy!***