Sometimes the SD card can become loose during shipping so it is not recognized by the Push3 when it is first connected. This issue is most commonly resolved by removing the SD card, cleaning it off, blowing out the SD card slot, and then reinserting it. The Push3 can remain powered while the SD card is removed and/or inserted. When reinserted the LED blinking pattern on the Push3 should change. Once the Push3 has mounted the LED blinking pattern should calm down to have a solid power LED (towards the edge of the case), a blinking internet LED (middle), blinking green innermost LED (green for good reads, red for failed reads).

If the above does not fix the issue, try reformatting the SD card to FAT32 and then reinserting it. 

If that doesn’t work then the SD card probably needs to be replaced. Make sure that the replacement is 16GB or larger.