An MRI cannot diagnose ADHD in an individual. MRI's can see trends and variations in brains of large populations. For example, an MRI of 1,000 people with ADHD might show a different sized <insert brain parts> compared to 1,000 people without ADHD.

However, a single person could have the same size <insert brain parts> as the average of 1,000 ADHD people and still not have ADHD, and a person could not have a significantly different sized <insert brain parts> and have ADHD.

To date, there is not a single biological marker nor empirical test that can be used to diagnose ADHD beyond a reasonable doubt.

We do not disagree. It's not necessarily faulty hardware but can be faulty software to reprise the initial expression.

But the reasons for faulty software are not necessarily understood.

(difference between a fault in structure vs. a fault in function)