The red light on the right of Canon 100d delete key flashes.

When the red light on the right side of Canon 100d delete key lights up or flashes, it means that image data is being written into or read from the memory card, or images are being deleted or data is being transmitted. At this time, do not open the memory card slot/battery compartment cover, take out the memory card and take out the battery. Otherwise, image data, memory card or camera may be damaged.