what does applecare's 90-day limited warranty cover?

ok so recently on august 12 , 2012 i was sitting on the couch on sears.comon my ipad 2 looking at shoes. and then my little brother comes and knocks it out of my hand an it cracks the camera area so i took it to the genious bar and i payed $249 to echange for a new one. (since i got this replacement ipad i have never let it go to 0% of battery so yeah just incase) last night i plugged in the ipad 2 and then when i woke up it wouldnt turn on? it still makes the noises of when i plug it in and when i plug it back out but the screen is completly black it does not turn on an its been charging all day. i even tried out the charger on my aunties' ipad 2 and it worked for her.i went to school and came back it still wouldnt turn on. i still have the receipt that they gave me when ever i went to the genius bar and it says i have 90 days of warranty i also called the apple care number and they said most likely theyll give me a free new one i have an appointment for tommorow. i dont know its just something in my mind thats doubting it would be free but i read what warranty does not cover and it's none of the things on that maybe if this has happened to you or you got a free exchange or you work there please help?