Retron 5 Controller won't turn on.

So I just got my retron 5, and I'm at the first time controller pairing.

The instructions say to "please hold the HOME button on your controller until the LED's begin to flash rapidly in order to initiate the pairing process."

The LEDs are not flashing. At all. I have held the button for several minutes. I have had it plugged in, first to the retron 5 itself, then to a fast charger for a while as well. It is still not turning on. Does the controller just take an absurd amount of time to charge? Is the button known to have problems? I don't know what's going on.