There the pair rifled through Burr's property in the living area before the girlfriend went to the bedroom where the man was sleeping.
Woken by her, Burr tussled with the girlfriend, Crown prosecutor Rebecca Mann told a jury in the High Court at Hamilton this afternoon where Burr and his son are on trial.
Concerned with what was happening to his girlfriend, the burglar went to her aid and hit Burr on the head with a wine bottle.
By now, Mann said, emotions were running high and Burr suddenly realised who the burglar was - having been the victim of his offending before.
Burr got his shotgun and "frogmarched" the pair down the hallway to the kitchen and ordered them on the ground.
With the pair under control, he rang police, his son Shaun Burr, and his neighbours.
He called 111 at 1.54am about what happened, saying he would "blow both their bloody heads off if they move", and that he knew the 17-year-old's identity.
He then continued warning if police didn't show up, he would "pull the f****** trigger soon".
Shaun Burr turned up shortly afterwards and it was then, Mann submitted, that the father and son set about "exacting retribution".
The male burglar was then "attacked", despite the pair of intruders being no threat to anybody, Mann said, as they remained lying on the ground.
Angry at the audacity of him returning, the father and son unleashed a "torrent of violence", with the teen struck about the head by Shaun Burr with pieces of wood which would soon shatter into pieces.
As that was happening, Burr Snr had his shotgun trained on the boy.
The young man will give evidence that it was Burr Jr who punched and kicked him in the head first.
His former girlfriend will give evidence about how she heard wood being broken and Burr Jr saying "this is what you get if you want to hurt dad".
The youth was left with lacerations to his head, significant bruising and lying in a pool of blood.
But the violence would continue, the court heard.
It was then the boy was asked to put his right hand flat on the ground. Burr Jr got a kitchen knife and began cutting through his little finger.
However, Mann said it wasn't a straight forward cut - instead "more of a hammering motion" was used.
The teen couldn't feel his hand anymore, Mann said. He will give evidence that Burr Jr was banging down on the knife to severer the finger which was ultimately cut off.
The teenager would also be told that his cut finger meant "that will teach you to steal, now people will know you are a thief".
The beating then continued, Mann said, with the boy receiving more kicks and punches to his head and body by both Burr Jr and Snr.
Evidence will also be given by neighbours who arrived to hear Burr Snr yelling "I will shoot the bastard" and saw the boy lying face down on the kitchen floor.
The neighbour will state that he thought the teenager was dead and that the pair were giving the intruder a "workover".
About five minutes later, the local police constable, Tony Schrafft, arrived. He seized the gun.
An attending police officer would also give evidence about how Burr Snr pointed at the boy on the floor saying "that's how you do it, you won't be f****** doing that again", before walking over and stomping on his lower back in plain view of the officer.
They would also testify how Burr Snr had the attitude that it was his house and he could do what he liked.
A St John Ambulance officer would also testify how Burr Snr protested about giving the boy Nurofen for pain.
The pair deny charges of wounding with intent to cause grievous bodily harm, wounding with intent to injure, maiming with intent to cause grievous bodily harm, and maiming with intent to injure.
Burr Snr faces two extra charges of assault and assaulting a woman.
'This is a case about fear'
Burr Snr's counsel Philip Morgan QC told the jury that all they had heard was the two victims' versions of events.
"There's more to come," he said. "You need to listen to the evidence, make assessments of people's credibility and truthfulness and apply common sense to what you have been told."
He said anything his client may have done was to protect himself and his son "from the man he considered to be very, very dangerous indeed" as although the boy was only 17, he "had been a frightening thing".
"This was not about retribution. This is a case about fear."
Simon Lance, defence counsel for Shaun Burr, said the reality was, Burr Snr was the victim of a "violent home invasion" where he was attacked in his bedroom while he slept.
"[Boy] was armed. He had a knife. He was about 140kg and the danger he posed was an ongoing danger."
The trial would be about self defence - or Burr Jr's defence of his father.
'He was hammering it with a stick'
The boy, now aged 19, was the first witness called.
His video interview was played to the jury where he explained how a stick was used to "hammer" the butter knife into his finger and help slice it off.
When asked by Mann what he was doing at the Burr house again, the boy replied "Oh, to go grab the car again".
Pointing to pictures of the kitchen, he was asked what happened there and responded, "I got a hiding on the floor".
The Crown will call 20 witnesses throughout the trial which is set down for five days.
A jury of three women and nine men will deliberate their fate. The trial is being overseen by Justice Grant Powell.
• The boy was arrested and convicted of aggravated burglary for his part in what happened. His girlfriend was dealt with by Youth Aid and went through a family group conference.
Both victims have automatic name suppression due to their age at the time of the offending.
