How do I update the firmware if I have issues?

Sometimes the best fix is to update the firmware on your JetBlack VOLT EMS Smart Trainer. Here's how to do it.

To run a firmware fix on your VOLT trainer follow these steps:


It is possible the your VOLT trainer firmware is compromised if you have the following symptoms:

  • VOLT light is solid red
  • Unable to connect to the VOLT
  • VOLT not showing up on any platform or device


Steps to resolve

  1. Download the nRF Tool Box App from iTunes or Google play.

  2. Download the VOLT firmware to your phone.
  3. Open the Tool Box App and navigate to DUF (Device Firmware Upgrade)
  4. Connect to Device (possible list below) Note: Do not connect other named devices.
    • JBOOT (VOLT default setting)
    • DUF…. (VOLT default setting)
    • VOLT
  5. Select Firmware
  6. Update

Please ensure procedure completes before disconnecting. Your light will start flashing once the update is completed.


If you are still having issues locating the VOLT, please try LITE BLUE APP to find and locate your Bluetooth device.



If your VOLT still does not show up on either the NRF or LITE BLUE APP, the issue is with your hardware unit. Please return to your retailer for warranty support.


We apologise for any inconvenience. JetBlack are working hard to include this procedure as part of the next app update.