"I went way over board this time."

That was the text Avi Raaj Prasad sent after his 8-year-old victim's skin peeled away - it was the final act in abuse the Crown called "cruel and sadistic".

The boy had suffered burns to about 20 per cent of his body after being held under a hot shower on March 25 last year.

That included burns to his chest and abdomen, right upper arm, both upper thighs and bottom.

Today in the Manukau District Court, Prasad, whose relationship to the boy was suppressed, was sentenced to five years and eight months in prison.

Crown prosecutor Evan McCaughan said today the child still had to wear compression clothing that made his skin smell - "He absolutely hates it."

The "horrific" offending had happened over four months. The boy had also been asked to stand against a wall and was burned on his bare bottom with a hot butterknife.

Those pre-existing and healing burns had been noted by medical professionals when the boy was taken to Middlemore Hospital on March 25.

Police had recovered the knife that was used to punish the boy.

Judge Richard McIlraith said the "tip of the knife was burned black".

The boy has since had nine operations and skin grafts for the burns were taken from his back and thighs.

McCaughan said the family had politely declined Prasad's offer of reparations as "no amount of money" could make the pain go away.

Judge McIlraith said the "barbaric" offending showed corporal punishment had been normalised in Prasad's background.

"It was clear you faced a difficult upbringing.

"You are in many respects a product of your upbringing."

Aggravating features included an element or premediation, the breach of trust and vulernability of the victim, Judge McIlraith said.

Another aggravating feature was the attempts to conceal the offending, he said.

Prasad had pleaded guilty to causing grievous bodily harm with intent, wounding with intent to injure and a representative charge of assault.

Defence counsel Emma Priest said it had been a "fall from grace" for a hardworking man.

"This is a truly exceptional case, if ever there was a case of a good man doing a terrible thing this is it."

By way of the explanation of the offending Priest said Prasad was trying to discipline the boy.

"He was trying to teach him. He was trying to help him learn the rules of the world."

Prasad's remorse was genuine, and that was corroborated by the fact he had offered more than $30,000 in reparations and had sought restorative justice, Priest said.

Prasad felt a sense of worthlessness, hopelessness and personal failure, she said, and his actions were a sad reflection of what he had suffered in his past.

A mitigating factor was his previous good character, she said.

"He has worked his whole life. He is a hardworking man."

A person, who cannot be legally identified, faces a charge of helping Prasad attempt to avoid a conviction.

That person's case was adjourned today for sentencing at a later date.