I don't know about your device but I believe the answer is "obviously, not". I don't think any of the devices have a "hard reset button" or it would be mentioned in the instructions.
As far as your update issues, what was the initial version of TOS installed? (and what is your OS partition size?) Can you access the CLI via ssh/putty/etc?
You might consider re-installing 5.1.67 (I'm not upgrading to 5.1.79 as it seems to have (re-)introduced some issues.)