A family of seven was trapped in their HDB flat after a personal mobility aid (PMA) battery exploded into flames in the corridor.The incident took place on Monday (Oct 20) at Block 756, Yishun Street 72.One of the family members, 30-year-old Rizwan, told Lianhe Zaobao that his family owns three PMAs — two for his elderly grandparents and one for his mother, 51, who works as a food delivery rider.They had bought the PMAs three years ago and had no issues as they used original batteries, he told the Chinese daily.But he was unaware that his mother had borrowed a cheap battery from someone as she felt her PMA battery did not last long enough.This battery burst into flames shortly after she plugged it in to charge after making a delivery.She told Lianhe Zaobao that there was a sudden bang outside the door and flames started shooting up from the window. Rizwan's grandfather initially tried to put the flames out with a fire extinguisher, but they spread too quickly. This caused the other mobility device to catch fire and the family had no choice but to close the door and wait for help. Read more