Firstly, check the Micro USB charging lead with another battery if possible. If this other battery doesn't charge, this would point to an issue with the cable or the charging port, so try an alternative.
If no other battery is available, try another Micro USB charging lead. If the issue does lie with the battery and not the cable, please do contact our customer services team who will arrange a replacement if the battery is within its warranty period.
If you need any further help after trying these troubleshooting tips, please get in touch!