Please follow these steps to update the firmware on your B12X/B15X speaker; 

1. Download the .dfu file with the new firmware version to your remote device from the download section of the respective BEHRINGER product page (click the product name above). 
2. Prepare the B12/B15X for a Firmware upgrade by following these steps:
   a. Power off the speaker.
   b. Hold the ENCODER KNOB.
   c. Power on the speaker. This will load a Boot Mode Menu
   d. Please select the option “Firmware upgrade” then press the ENCODER KNOB.
   e. The B12X/B15X is now ready for the firmware update.
3. On your remote device, select and hold the .dfu file until a pop up window offers options for file transfer.
4. Select the option for sharing via Bluetooth. (NOTE: Some devices need to be paired with the speaker before file transfer.)
5. Select the B12X/B15X speaker for file sharing via Bluetooth.
6. During the file transfer, the LCD screen will display the download progress.
7. After the file transfer is complete, the B12X/B15X speaker will automatically restart and return to the usual startup screen.