For the benefit of anyone else suffering with this problem... in my case, substituting a quality Ethernet cable solved the problem. The one bundled with my bridge caused the connect lights at the port to light up, but was evidently not able to pass data reliably. I twigged to this when I noted that an IP address had not been requested from my DHCP server. After swapping the cable and doing the major reset, the update was able to complete and the unit began to work properly. But I wasted two days getting what should have been idiot proof to work...
Thankfully, Acu-Rite redeemed themselves by replacing my 5-in-1 (that didn't display wind direction) in a prompt and relatively painless way.
Thankfully, Acu-Rite redeemed themselves by replacing my 5-in-1 (that didn't display wind direction) in a prompt and relatively painless way.