Couple of things to try:
1) In the lower right corner, near the power plug there should be a little red light that comes on when you power it up. After a few seconds the green light next to it should blink. If the green light is not on or blinking it is the SD card. May sure you have inserted the SD card.
2) remove the SD card and reinsert it. Power it up again.
3) Still not working?
– You can reload the image on the SD card by following these instructions
– Send us your order number (amazon or Boolean GirlTech), your address and we will send you a new SD card. firstname.lastname@example.org is the email address.