How can I fix my diplomat dishwasher?

I have a Diplomat dishwasher which was already installed when I moved in and has no manual so no idea what model it is, sorry. My problem is that when I turn it on it either continually bleeps and the on/off light flashes or it just goes through a final rinse cycle in which the water does not get hot and also doesn't dry dishes. I hope someone can help even though my information is a bit vague.