But the alleged victim, whose mother called triple-0 and screamed about there being intruders in the house, claims he cannot remember such a thing.

Kerrod Matthew James Edwards is on trial in the ACT Supreme Court, having pleaded not guilty to committing an aggravated burglary in company while armed with an offensive weapon.

Opening the Crown case on Monday, prosecutor Sarah McFarland told the court Mr Edwards had trespassed into a Kambah home about 3.30am on August 12 last year.

The accused was there, Ms McFarland said, to get the keys to a red Mazda 3, which he claimed was his.

She said he stood over a man who was in bed and threatened him with a machete and a tyre iron while a co-offender, Melissa Baker, stood guard in the bedroom doorway.

The prosecutor said Mr Edwards was then arrested nearby while in possession of the Mazda 3 keys.

But defence lawyer Sam McLaughlin said this version of events would be proven wrong, and claimed Mr Edwards had actually entered the house with permission to retrieve his keys.

Subpoenaed to give evidence on Monday, the alleged victim repeatedly insisted he did not know why he had to appear.

After hearing audio of his mother calling triple-0 and screaming at people to get out of their house, he said: "There were a lot of arguments around that time."

"I don't know what's happened that was that bad for her to ring the coppers and carry on to where it is now [in court]," the man said.

Asked about the Mazda 3, he said he had borrowed it from a man named John, then left it for "John" to pick up after it got a flat tyre.

But Mr McLaughlin suggested the man had in fact promised to give this car to Mr Edwards to make up for damaging a Holden Commodore that he had borrowed from the accused.

He claimed that on the morning in question, the man let Mr Edwards into the Kambah home through a laundry door.

Inside, according to Mr McLaughlin, there was "a discussion" about the issue and the man "was apologetic to Mr Edwards about not giving him the keys to the car sooner".

The man agreed with Mr McLaughlin when the defence lawyer suggested that if there had been an armed invasion of his bedroom, he would recall such a thing.

However, the man's mother gave a wildly different account of things.

She told the court she had woken up on the morning in question to the sound of her son screaming, "No. No, bruz. No."

The woman recalled going into the hallway to find "a big girl" standing in her son's doorway "like a bouncer".

"I've never seen her from a bar of soap," the woman told the court.

She said this "bodyguard" would not let her into her son's bedroom, in which she could see Mr Edwards leaning over her son with a knife and "mumbling something".

The woman told the court Mr Edwards and her son had been arguing around that time because "they had swapped cars or some shit", but nothing gave Mr Edwards the right to come into her home in the middle of the night.

She said the intruders refused to leave, despite her screaming, until they realised police had been called.

"It was a terrifying moment," she said.

Mr McLaughlin challenged the woman on the reliability of several aspects of her evidence, including her descriptions of weapons.

He pointed out that at some points she had described Mr Edwards holding a machete to her son, while at other times it had been a kitchen knife.

In another version, Mr Edwards had brandished a kitchen knife and picked up a machete from her son's room on the way out.

But the woman, who was emotional throughout her testimony, continually shouted over Mr McLaughlin and complained she was wrongly being treated "like a liar" when her family were the victims.

The judge-alone trial, before Justice David Mossop, continues.