If you would like to offer flat rate shipping to HI and use the quote for the others you will need to add in a new flat rate shipping rule for HI and then update the current FedEx shipping rule.
To make the HI rule you will first need to ensure that you are storing the shipping state that was selected on the checkout page in a session variable. Once the variable has been set you can then check this variable in your shipping charge rule to see if it is set to HI.
On your confirm page you should go to bindings > form data then select the checkout page, this will get all of the checkout bindings onto your confirm page for you. Next go to Server Behaviors > eCart > general > set session value. For the trigger you can use the lightning bolt to select the shipping state select list, then give you variable a name like shipping_state and for the value set it to the posted shipping state value.
Now that the session variable has been created you can make the new shipping charge rule. In the eCart object go to the shipping tab and add a new rule. Give it a name the add in the conditions for the trigger. The first condition will be if your shipping_state session variable exists, the second condition will be if it is set to a value of HI. The for the calculation portion you would just choose flat rate and set the amount.
You will also need to update your other shipping charge rule, edit the rule and add in a condition to the trigger. Set the condition to your shipping_state variable not being equal to HI. This should get it the way you would like it. Let us know if you have any other questions.