Depending on the software version your C40 is running, there are a few methods you can use - although almost all will require the Serial Port.
Pre TC7 - within 60 seconds of the endpoint booting, you should be able to log in via the serial port with username "pwrec" to start the password recovery process.
For TC7 (again - must be done in a very short period of time after then endpoint has booted) - use the "factoryreset" user to log in, then do an "xCommand SystemUnit FactoryReset Confirm: Yes", followed by an "xCommand Boot"
If you've tried all other methods, you can try performing a factoryreset from the U-boot environment.
See pages 49 - 51 of BRKEVT-2805.
Wayne
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