Capturing and reviewing the console output while you flash the board should give you a hint where and why it's failing.
A few more things to consider:
- How are you powering the board?
- Could you be using an underpowered USB port to power the board or using a cheap USB cable with low quality conductors?
- If you're powering only via USB, have you tried connecting an external power supply to see if the failure is power related?