Police and paramedics arrived and Mr Phillips, who was originally from Berwick, was declared dead by 09:00, the court heard.
Officers found a 1.5m-long (5ft) metal bar used to lift weights with one end covered in Mr Phillips’ blood in Lyons’ flat, Mr McKone said.
Lyons’ DNA was found on the opposite end of the bar, the court heard.
The court heard he was initially interviewed as a witness and asked officers if they had ever killed anyone before saying “I killed someone this morning”, then adding: “I’m only joking.”
He also said he had paranoid schizophrenia, having been diagnosed in 2015, but had stopped taking his medication a week before the attack, the court heard.
Mr Philips was found to have been struck multiple times about the head, with his death caused by catastrophic brain injuries, the court heard.