When you say its not draining the water away if it leaving it full of water?
If you restart the dishwasher will it drain the water out at the start?
Ok the draining may be a blockage so you need to check the filter inside the dishwasher. Remove the big mesh filter and give this a good clean out. As sometimes it gets gunged up underneath.
If it was blocked under there then just retry the dishwasher as this can actually stop it from heating up as well.
If that's not the case then for a no heat fault its usually either the heater itself or the control board.
Remove the plastic control panel at the top to access the board.
Then remove the control board and open the plastic caseing.
From there remove the board and see if theres any dry joints or burn marks you can resolder.
If the control board looks ok then you need to remove the dishwasher and remove the right hand side panel.
There you will see the heater at the back of the tub at the bottom.
Check the resistance of the heater with a multimeter and see if faulty.
If so then the heater will need to be replaced and that should cure the fault.
Check them out and see what you find and let me know.