A Bimberi youth centre detainee who drove a stolen buggy during a riot was being "childish" and "immature" but not violent like his alleged co-offenders, his defence lawyer has said.
The 17-year-old pleaded his case to Magistrate Robert Cook on Monday, having previously admitted he rode in a motor vehicle without consent, and removed a fire extinguisher from the detention centre.
Prosecutors earlier abandoned a third charge of attempting to escape from custody.
Neither the 17-year-old nor his alleged five co-offenders - who are also before the courts - can be named for legal reasons.
The ACT Children's Court on Monday heard the boy was let out of his cell by another detainee on the night of August 26, 2019, in the midst of what his defence lawyer, Tom Taylor, called a "nasty" riot.
The 17-year-old walked around the facility with the other boy and climbed onto the roof of a demountable. He got off at one point to retrieve a fire extinguisher, and later, drove laps of the centre in a maintenance vehicle, which was similar to a golf cart.
Police allege that minutes before, other detainees attacked youth centre staff. One worker allegedly had a knife held to her throat, while another had his head split open with a desktop computer.
CCTV of the incident was played to the court on Monday. Mr Taylor told the court: "[The boy's actions aren't] of any big significance in the scheme of things.
"It was ... opportunistic and immature of him.
"Some of his offending simply was just childish."
Mr Taylor argued the boy should be treated "separately" to his alleged co-offenders, given he wasn't involved in the alleged assaults on youth centre workers "at any stage".
He said the boy had been dealt a "hand of cards in life that no one should be dealt" and was a victim of childhood trauma and neglect.
In sentencing the 17-year-old, Mr Cook said the relatively low severity of the boy's crimes was abundantly clear - but they were aggravated by having been committed while he was in custody.
He said there was no evidence before the court that the boy was involved in planning the riot.
"You need to do things that are in your best interests - not the interests of your friends," Mr Cook said.
The boy told Mr Cook he wanted to get "on the straight and narrow" when he was released from the youth centre, and address his issues with substance abuse.
"I know I had a choice [not to leave the cell]. I just wasn't [thinking] straight at the time," he said.
Mr Cook sentenced the 17-year-old to another three months in jail, and ordered him to pay a $300 fine. The jail sentence will be suspended from April 2 on the condition he abide by a good behaviour order.