what you need to do is adjust the formulas because it is looking for the current sheet that you have changed but cannot find the name.

The easiest way I believe to change the sheet name then change all of formulas by select all the cells with #REF & use Ctrl + H. Type in the old name into the find what box, and the new name into the replace all box, then hit replace all.

This should sort of all of the #Ref