You cannot launch the Local Maintenance Terminal to run MML commands without a recognized COM port.

The BBU3900 USB driver is a software component designed to enable communication between a computer and the BBU3900 device, a battery backup unit (BBU) used in various applications, including data centers, telecommunications, and industrial settings. In this review, we'll evaluate the performance, reliability, and overall quality of the BBU3900 USB driver.

Windows 11 refused to install the unsigned driver, citing "security policy." She rebooted into "Disable Driver Signature Enforcement" mode, only for the driver to fail with the error: "This device cannot start. (Code 10)."

She tried compatibility mode for Windows 7. She tried Windows 8. She even tried running the installer as the built-in Administrator account, which she had to re-enable using a command prompt she found on a Reddit thread from 2015.

: Check that the BBU is fully powered and the RUN indicator is flashing normally before attempting a connection.

Which are you connecting to (e.g., UMPT , GTMU )? Are you getting a specific error code in Device Manager?