The victim answered his door in Deptford to a man who posed as a deliveryman, Scotland Yard said.
The impostor then looted the victim’s home with two other men, and ordered him to open his safe.
When he said he did not know the code, he was beaten, kicked and dragged into the basement, where his attackers then poured hot water from a kettle over him, police said. His face, neck and body were burned.
The Vietnamese man required immediate hospital treatment after the attack on December 22 but has since been discharged.
His attackers, who wielded a mallet and possibly an imitation firearm, were not able to steal anything from the home.
“As the victim was being assaulted, he feigned unconsciousness, and when the suspects stopped the assault he attempted to get help,” a spokesman said. “He managed to shout through a vent in the basement and alert a passing neighbour who asked if everything was OK.
“At this point the suspects fled the house empty-handed, running out through the front door before jumping into a vehicle and driving off. The neighbour raised the alarm and called police.”
The suspects have not been found during the investigation since last month’s attack. They are described as black men, about 5ft 11in, between ages 20 and 25 with English accents.
