how much would it cost to replace the whole computer system of a 2010 ford fusion?

What is your question?

I bought a 2010 ford focus at the auction. While trying to have the whole vehicle checked, I am told that "there are problems with the computer". I don't know what those problems are, but since I got the car for a very good price, I am trying to decide whether it would be worthwhile to replace the computer myself. The decision is hinged on how much it would cost me.