"I thought that was suss, you don't do this to family," she said.
Once inside, they set about looking for keys "to the old dude's car" before going into Burr snr's bedroom.
"The old dude woke up and we started fighting. He was shocked at us in his home."
The boy told her to hit him with the wine bottle - she did - but the bottle didn't break.
Shortly afterward the boy hit him with his bottle and it smashed.
She and Burr snr continued fighting, exchanging punches before Burr snr gave up and told them to take his car.
The boy went to look for keys in the kitchen and Burr snr took the opportunity to put some clothes on.
The girl said she left the room, then she noticed Burr snr had a shotgun and was pointing it at them in the kitchen.
"He was threatening us. He was just telling us to get on the ground or he will shoot us."
The girl, who became emotional in the dock remembering what happened, said she didn't want to get shot so she lay on the ground.
Asked how the boy was behaving, she replied, "like an idiot".
"He was picking a fight with the wrong person, [he] most likely would have got killed that day ... that's not something to joke around with."
She said the boy was being hit hard enough by Shaun Burr to the point "he was bleeding".
"I was laying in his blood."
She said the boy "was begging for his life" saying, "please stop, I beg you, I will pay for everything even your car'," she said.
She couldn't look at the attack taking place because she "hates violence".
She testified that it was Shaun Burr who grabbed the boy's hand and then hammered it with a hammer, to numb it, before "he chopped his finger off".
Asked by Mann if the boy was making any noise, she said "no".
"It's like his soul left his body."
When questioned by Burr snr's counsel Philip Morgan QC, she said the boy was provoking the Burrs by refusing to place both his hands on the floor in front of him.
"Then they said, 'get your hand out, get your hand out," Morgan asked her.
"Yep," she replied.
When questioned by Simon Lance, counsel for Burr jnr, she confirmed she broke up with the boy after the incident because she didn't want to be with him anymore.
She also defended her earlier comments that the boy had begged for his life, telling Lance he said it while he was lying on the ground.
However, she did state the boy deserved the "hiding" as he had lied to her family.
"Well, he did deserve it, from my point of view."
Earlier today, the teen boy wrapped up his evidence and told a jury he was armed with a wine bottle, knife, and a torch when walking into Burr snr's room as he slept.
He also admitted breaking into Burr's house just a week prior to the violent incident, to again steal his car.
"Then you woke him up by saying 'give me your f*****g keys or I will kill you?" Morgan asked.
"Yeah, that's what I said," the teen replied.
Burr, known as Bill, and his son, Shaun, deny 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 after allegedly attacking the burglar.
Burr snr, 66, faces two extra charges of assault and assaulting a woman.
The trial is set down for the week.
* The teen girl pleaded guilty to a charge of burglary at the time and was dealt with by youth aid. The boy was convicted of aggravated burglary.
