The customer that took his Focus in to a Ford main dealer only to have them fail to diagnose the car first time.
They charged for a throttle body, only to have the fault recur, then they wanted to charge for an ecu.
He complained like merry hell and eventually they agreed to do the job of fitting the ecu for cost of parts only, so some saving, they insist that the Throttle body was faulty and would have caused the ecu fault. I do not see that as possible. However.........
As to the battery: the car had never been jump started, but had a new battery a couple of years ago after it became sluggish at starting.