for( i='A'; i<='E'; i++)
//this means for i = 65 and as long as i <= 70, or something like
//that. I suspect you need something more like:
// for(i = 0; i < 5; ++i)
cout << i << " ";
for(j='A'; j<='E'; j++)
//same here, see above
randomLetteri = getCharacter(totalPercentArray);
//randomLetteri is never declared, but may well be typo
cout << boardArray[randomLetter][randomLetter] << endl;
//when the indexes of a 2D array are the same you will only
//see the values on a diagonal of the table (eg A1, B2, C3).
//Use i for first index and j for the second.