Since Firmware 3.x we have add a new Bootloader and you could update your PCAN-USB Pro FD very simple with our PEAK-Flash Tool --> link. This Tool includes always the latest Firmware vor nearly all PEAK-System CAN/LIN Devices.
If you own a PCAN-USB Pro FD with a Firmware 1.x or 2.x please follow this Steps:
Download the needed Bootloader Firmware and Documentation how to flash older Devices with the new Bootloader from this link.
or check this page: https://www.peak-system.com/produktcd/ Please read the Documentation and follow the steps as explained.
To flash the MSD-Bootloader to the Device, you need to use a Windows 8.1 or Windows 7 System

W10 / W11 is not supported by this old Tools.
When your PCAN-USB Pro FD have once a Firmware >=3.x, you could use the PEAK-Flash Tool to bring it very simple up to date