Coroner Nerida Wilson found James Daniel Tabuai died from being slammed or thrown against a wall or floor on February 1, 2013, just days before he turned seven months old.

He fell unconscious almost simultaneously with the force that caused his fatal injury, but emergency services were called about an hour later, Ms Wilson said in her findings delivered on Thursday.

James was with his then 21-year-old mother Synoa Tabuai at the Edmonton, Cairns home of his grandmother Germaine Lenoy, with Ms Tabuai's sister Danielle and her partner Ehammed Anderson also present.

Mr Anderson told the inquest James was crying more than usual, while his mother was "yelling, growing louder and more frustrated" earlier on the day he died.

Family said the baby was "breathing funny" about 9.30pm, but an hour later Mr Anderson said he woke to find James not breathing, his limbs limp and lips blue.

He started CPR while Ms Lenoy called triple zero.

James was taken to hospital by paramedics but could not be resuscitated.

An autopsy found "multiple traumatic episodes estimated to have occurred from weeks to days to moments before James' death, including a shaking incident several days prior to death and impact to the head several weeks beforehand".

Ms Wilson concluded James sustained a head injury that left him with a severe but not fatal bleed on his brain weeks before his death, while days before he was shaken so hard his spinal cord and brainstem were damaged.

The baby had a skull fracture experts found could not have been caused by a fall from a bed or rough child-handling.

Ms Wilson said the inquest was held after a police investigation and state corruption watchdog hearings because the lack of knowledge claimed by the four adult carers in the home regarding the injuries on the evening James died "remained implausible".

She found none of those present have claimed to have knowledge or had an explanation since James' death despite tensions and fallings out between family members since.

"It is absolutely implausible given the non-accidental force that was required to cleave James' skull such that it caused a bilateral fracture - and a massive haematoma and brain swelling - that no one knows or remembers anything," Ms Wilson added.

The coroner was satisfied the police investigation was "of the highest standard" although it did not lead to criminal charges.

Ms Wilson found the lack of detail about family members' movements in the two hours before 10.30pm "is deliberate and has been cultivated to cover up the true nature of events".

"I am satisfied that all members of the family present that night know what transpired," she concluded.

Australian Associated Press