By Hyunjoo Jin SEOUL (Reuters) – Samsung Electronics Co Ltd on Monday said faulty batteries caused its flagship Galaxy Note 7 phones to catch fire and announced steps to avoid repeat incidents, as it tries to restore trust and regain momentum in the smartphone business. The announcement came more than three months after Samsung scrapped the short-lived competitor of Apple Inc's iPhones, wiping $5.3 billion off its operating profit in one of the biggest tech failures in tech history. While Samsung Electronics' mobile division is expected to have bounced back from the Note 7 failure during the fourth quarter, investors remained cautious about the outlook due to uncertainty about how the Note 7 fires would affect sales of future flagship devices.