A baby was "shaken and battered" by his father days before he died of catastrophic injuries, a court has heard.
David Hollick, 29, denies murdering his six-month-old son Kairo Jax Hollick, who died in his mother's arms at Birmingham Children's Hospital on 12 February 2020.
Kairo had suffered a non-survivable brain injury, at least two skull fractures and a fracture to his right arm, the jury at Birmingham Crown Court was told.
Prosecutor David Mason KC told the court Kairo was in the care of his father when he was fatally injured on 9 February, saying it was their case the boy "had not only been shaken violently, but his head had been bashed at least twice" with a hard object by Hollick.
Mr Mason said Hollick's ex-partner Adina Johnson had dropped their son off at his home as usual on 7 February for the weekend.
The court heard Hollick phoned Ms Johnson at 4.30am on 9 February but she did not answer because of the time, instead messaging to say she would call him back later.
Hollick then sent her a message telling her to "ring him back, it's about Kai".
Mr Mason told the jury: "What had happened? Well, I'm afraid that the sad reality of this case, ladies and gentlemen, is that to date we have no idea of what really happened to Kairo.
"David Hollick has so far failed, we say, to tell anyone the truth as to what he did to his little son.
"According to his account to his family and then to the police, the most that he ever admitted is shaking Kairo, but only after finding Kairo unresponsive."
Father claims he shook son to 'wake him up'
Kairo was driven to Walsall Manor Hospital, where Hollick told medical staff he had heard his baby son crying before he stopped breathing and claimed he only shook him to "wake him up".
Scans showed Kairo was suffering from a bleed on the brain and a decision was made to transport him to Birmingham Children's Hospital, but despite their specialist facilities, nothing could be done to save him.
Experts are expected to tell the trial Kairo's unsurvivable brain injury happened at the same time as the fractures to his skull, while a fracture to his right forearm could be timed between three and seven days before his death.
Hollick denies murder and an alternative charge of manslaughter.
The trial is expected to last three weeks.