6254BD scope not recognised by driver

Keybored02

Hello, I recently acquired a 6254BD oscilloscope. Unfortunately, when I power it on, it doesn't connect. I have installed the latest drivers from the download page, but the device is still not recognized by Windows.I've also tried thefirmware upgrade suggested on the forum, with the tool that support agent Amy uploaded, but I cannot get the tool to work (it doesn't let me upload the firmware file). The newer version of that tool doesn't work either (scope not recognized).
Finally, I tried opening the scope: when I connect it via USB, I can see a green LED near the FPGA on for a few seconds, then it turns off again. I can see that the scope draws 300mA when connected to a power supply via USB.
I suspect that it has something to do either with the USB controller or the EEPROM memory. I really appreciate any help you can provide. Many Thanks!
Scope board is labeled 64D01521, dated 20160416, serial DSO6xx4 v1.06. I have access to serial programmer and a Jtag debug tool for the FPGA.
Many Thanks!