How can I fix my Kenwood KDW8ST2A Stainless Steel Dishwasher?

I used my dishwasher for the first time yesterday, and it started overflowing - we got the E4 error code. So we emptied out all the water and tried to run a cycle with no tablet just to clear it. We could power on the dishwasher but then all the lights went out and we are not able to select a programme to run?!

Please help!!!