SEOUL, South Korea (AFP) — Samsung has told customers worldwide to stop using their Galaxy Note 7 smartphones after a spate of battery explosions threatens to derail the powerhouse global brand. It is the latest in a string of lithium-ion battery fires on products ranging from laptops to hoverboards to planes — and a reminder that pushing the technology envelope can sometimes be problematic. Here are some things to know about Samsung’s snowballing safety crisis, […]