"Could not open device" might mean that you don't have the correct Windows driver loaded or that you have some Qualcomm driver loaded or that something is trying to use your device already.
"Could not write device" depends
when and under what circumstances it occurs.
As I don't have a Poke5 or proof that a loader for it exists, I can't say much.
You can try my
test utility
Code:
C:\>winusb 05c6 9008
Found generic device at 05c6/9008
Path: \\?\usb#vid_05c6&pid_9008#8&1265ce96&0&4#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
In bulk endpoint 81
Out bulk endpoint 01
Everything ok