[HighAltitude]

In the process of configuring my new Spektrum DX9 to interface with my Revo board, I inattentively switched the USB port from "Telemetry"  to "RC radio" (or something similar).  Now Librepilot can't find the Revo.  I've tried several options on the Download screen, but still no joy.  Suggestions?
Thanks

[hawkview]

Go to gcs firmware page click the erase and upgrade button and follow the instructions, that will bring the board back and you will have to start again eg setting it up

[HighAltitude]

I should have mentioned that I already tried both Upgrade and Upgrade and Erase on the download page.  Those are the only buttons that aren't greyed out and inactive. 
When I try both, the application times out while waiting to recognize the board. 
The LED's on the Revo do their usual blink sequence when the USB cable is plugged in, so it must be getting power. 
Is there a way to restore the board to it's factory default configuration that doesn't necessitate a connection to the GCS?

[hwh]

Are you clicking "upgrade & erase" with the board disconnected?   And then connecting it when it tells you to?

[HighAltitude]

Timing is everything!!!!!
USB Telemetry is now working again.
Thanks for the guidance.

[TheOtherCliff]

For future readers of this thread, there may be a way without erasing all your settings.  I haven't actually tried it:
- start with FC powered off
- go to Firmware page in GCS
- press Rescue and immediately plug the FC into USB
- it will recognize the board and enable some other options
- press Safe Boot to boot up with default settings
- go to Configuration -> Hardware and set "USB HID Function" to USBTelemetry and set "USB VCP Function" to Disabled and save it

Now you should be able to boot up normally and you will only need to redo the Configuration -> Hardware page.