This is a problem i have had alot of times,
I agree with the previos answers but it could also be the CR board. But most likely it is the printhead that has given up.
I had this problem resently but since the head was new i made the wrong conclusion and left that out of the list of potential problems. Instead i changed every flat cable, the cr board and when that did not do it, i change the motherboard aswell, only my head had a short and blew the new mainboad.
I was told, that if you change mainboard, make sure to change the head at the same time. And also the two head flat cables. But if you need to change teh mainboard flat cables, make sure they are in the right possition, if not you run the risk of damageing the mainboard.
/D