Amrita have 4 campuses, To get CSE branch in Amrita Main campus which is situated in Coimbatore, your rank should be under 2500 (other state) and under 8000 (hot state).

It is difficult to predict marks to get this rank as Amrita don't release marks vs rank data. but you should try to get 250 marks out of 300 to get good rank in AEEE exam.

Good Luck.