After you place the sink down chances are if you pick it back up again you won't put it back in exactly the same place. I would clean it all off and figure out how to mount the heatsink properly as that was probably the reason it got so hot. Then when you have figured it out just place a small rice sized 'dab' of paste on the centre of the cpu, and place the heatsink on top, you should'nt lift it off again to check.