SAS sniper Danny Nightingale to be tried again

Danny Nightingale's conviction for illegal weapon possession was overturned, but he faces a retrial. His family was surprised by this decision. Due to a brain injury, he is unfit for active service, leading to a medical discharge. His defense argues the injury caused him to forget possessing the firearm. Regardless of the trial's outcome, his military career is over, but he has job offers as a civilian.

What are the implications of the retrial for Danny Nightingale and his family?

What impact did Danny's brain injury have on his military service?