Ubicom apparently built in a self-protect mechanism into this line of routers chipsets. If the flash update doesn't go 100% proper, it doesn't take and the router keeps the current firmware.
I guess this is a good thing.....unless you are trying to self brick it....
Frankly, just get a hammer out and do it the easy way if you are that willing to blow $100....
you could easily just disable the wireless and use the thing as a decent 4 port Gb switch....