Why does the Status LED keep blinking blue in a fast sequence even though a micro SD card is inserted in the card slot?

Why does the Status LED keep blinking blue in a fast sequence even though a micro SD card is inserted in the card slot?

In most cases, this will be caused by a wrongly formatted SD card which results in the unit not recognizing the SD card at all. All SD cards need to be formatted in the EXFAT file system in order for the unit to detect the card.