The following simulation illustrates a Hosted Payment Form Load error during order entry where a Braintree Connection is primary and a PayPal Connection is the fallback. 

Enter the order header making sure to use ERR02 in the Customer PO field and the payment instrument designated for credit card. 

Enter the order details and advance to the payment screen.  Now, when the payment screen loads you will experience a simulated timeout of the primary connection.

Once the timeout completes the fallback payment screen is displayed.

Once payment is complete you can see it in the fallback (PayPal) account and not the primary (Braintree).