DFU util seems to randomly produce this error, but it doesn't actually make any difference.Resetting USB to switch back to runtime mode
error resetting after download: usb_reset: could not reset device, win error: The system cannot find the file specified.
BTW. I tried removing the "reset" option from the DFU upload, but it stops the upload working.
But as this is more of an erroneous error message than a real problem I didnt pursue it further.
Re: Maple mini getting locked in DFU upload mode
Either its actually locked in upload mode (DFU), or the Maple mini has attempted to trigger USB enumeration and your PC / Mac has not noticed the enumeration.
If its actually locked in DFU upload mode, the LED on the maple mini will continue to flash quickly (indefinitely)
This can only really happen under 2 conditions.
(a). The "Button" is being pressed on the Maple ini
(b). The data in the sketch is not being recognized by the bootloader as a valid program that it can run
If the LED is not flashing quickly, the bootloader has handed control to the sketch and the sketch is running.
Upload a sketch that flashes the LED slowly e.g. delay(1000) and see if the flashing on the LED changes from quick flashing to the slow (1000ms) flash in the sketch)
I suspect in your case the sketch is running, and that your PC has not spotted the signal to re-enumerate
The other possibly option that should not be discounted is that your Maple mini board is faulty e.g. the circuit which resets the USB (to force re-enumeration) is not working e.g. dry joint or faulty component.