A 90-year-old woman was killed after her grandson hit her with a wooden plank when she unintentionally damaged his new mobile phone. The 22-year-old had kept the phone on charge in the drawing room of their house at Kadirenahalli in Banashankari on Monday night. His grandmother Lakshmamma, who had poor eyesight, failed to notice the phone and accidentally touched it while walking in the room. The cellphone fell down and the screen cracked into pieces. Shivaraj, who heard the noise, rushed to the drawing room and found the mobile phone damaged. In a fit of rage, he grabbed a wooden plank and hit Lakshmamma on her neck. She collapsed with pain. Other members of the family shouted at Shivraj for hitting Lakshmamma, and took her to her bedroom and nursed her to sleep. On Tuesday morning, Lakshmamma did not respond when family members tried to wake her up. They shifted her to a nearby private hospital where she was declared brought dead. Banashankari police sent her body for postmortem and arrested Shivaraj.