Hammerheads BT - Not visible for Bluetooth pairing

I've only just got this pair of earphones out from the box. Followed the instructions of charging it first to full battery. I was able to successfully pair it the first time to my Razer Phone 2 and play music over it. But when I switched the Hammerheads off and on, it did not automatically reconnect. I've tried everything from removing the pairing from my phone, to resetting my phone. I was unable to 'see' the Hammerheads via Bluetooth. I've tried with other phones and my laptop and they were unable to find it too. I have been following the manual of holding the multi-function button from 'off' status for 5 seconds and more to get into pairing mode. I can hear the beep every 15s but oddly the LED remains at solid green, not blinking green as described in the manual. Is there anything that I am not doing correctly? Please help. Thank you.