My friend's PS3 has some light of death we are guessing! It will turn green, then will turn blue & green, then it turns green & yellow, then it turns blue & yellow. Then just yellow followed by 3 consecutive ''bleeps''.

This is known as the yellow light of death (ironic i know because it blinks a red light). This is caused when the unit overheats causing solder on the board to melt and bridge(connect). Once this happens it shorts out the board causing the error you have now. Contact Sony and see if the unit is still under warranty.