Hi!
With this approach, I have successfully updated the WS90 several times.
The procedure should be transferable 1:1 to the WS80:
mini howto updating the WS90 sensor
1. plug in USB cable
2. reset WS90 device (left button on WS90)
3. start DfuSeDemo.exe
4. choose upload file (middle button in the lower area)
5. mark "Verify after download"
6. start Upgrade (button)
7. leave DFU mode (button)
8. unplug USB cable
9. reset WS90 device (left button on WS90)
Especially point 7 and point 9 are often forgotten and therefore lead to problems.
But I don't have a WS80 here and on the HP2551C I have the WS90 disabled. So it might look different there.
Oliver