I just purchased the H9 and only had it a couple of days. Pairing was great the first 3 or 4 times i used it then tonightt it would not pair no matter what i did.
When I run into any problems pairing my H9, the first thing I do is turn Bluetooth off and then on again on the H9 by pressing the X, Y, and Z switches simulataneously (twice). Oftentimes, I'm having trouble b/c I was using my H9 with another computer or iOS device, and doing this will break that connection.
If this doesn't work, I'll reset the H9's system settings by turning the H9 off and then turning it on again with the HotKnob switch (the button in the upper left hand corner of the H9). This almost always clears up whatever problem I'm having.