Reginald Roy, also known as Yunupingu, 17, died months after being discharged from Royal Darwin Hospital's youth inpatient unit (YIP) in October 2020.
He was found dead at the bottom of a power pole at Minyerri, southeast of Katherine.
Coroner Elisabeth Armitage said the cause of death was high voltage electrical injury due to mental disorder/psychosis.
"This was not a child that 'fell through the cracks' of service delivery, it was as if he fell from a cliff," Judge Armitage said in her inquest findings on Friday.
The 17-year-old had lived mainly between the Ngukurr and Jilkminggan remote communities, primarily with aunts and uncles. As well as having an intellectual impairment he suffered from hearing loss.
His school attendance declined from age 10 until 2018, when he did not attend at all.
From 2009 to 2020 the territory's department of children and families received 13 notifications about his wellbeing, including being the victim of domestic violence.
He was also reported for sniffing petrol and by Christmas 2018 the teen's mother said that he was hearing "evil". The following year family observed him experiencing visual and auditory hallucinations.
By early 2020 he was admitted to the YIP and sectioned after being diagnosed as acutely psychotic with brain injury due to "chronic volatile substance use".
After his condition improved he was released, but his behaviour soon escalated and he was sectioned again.
He was discharged once more on March 31 with "low grade psychotic symptoms", but Judge Armitage said it was identified that if he was not appropriately supervised he was considered to have a moderate to chronic risk of misadventure and a moderate to high risk of substance abuse.
He did not see or speak to a health professional after April 9, or receive his monthly medication in the six months that followed.
"This was the tragic death of a 17-year-old who was not afforded basic mental health care for a period of over seven months after he left the Youth Inpatient Unit at Royal Darwin Hospital," Judge Armitage said.
"Tragically, within nine days of his discharge into the community he was lost to mental health services."
The coroner's recommendations include the YIP referring young people from remote communities to Child and Adolescent Mental Health to engage service providers and establish care arrangements and support for young people and their families within the community.
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