Remote won’t pair light blinking but stuck on pair your remote screen

Gigiheart, the 3820 requires the cable with the "Long-range Wi-Fi receiver", so make sure you're using it.  It's possible that the cable is bad right out of the box (especially if someone swapped it out and returned the stick).  If you just bought it, you may want to just return it.

For help on pairing it, you can try:

How to set up your Roku® voice remote | Official Roku Support