Hhmm.. well 'Android' didn't cause the crack did it!!
If HP wanted to be awkward, I suppose they could argue that installing Android nullifies their warranty agreement with you. I don't think that has ever happened though.
Also depends if they decide to repair yours, or send you a 'replacement'.. can you specify that you want YOUR actual machine back?
I have seen a app in preware the at will remove android. Don't know how it workss but worth a try then run a doctor after that. There are forum posts of people doing it then having their TP fixed/replaced.
Hope it helps.