My Obi100 just stopped working as well.
I used these instructions that someone posted to the forum:
Download and save the .fw file from this link:
http://fw.obihai.com/OBi110-1-3-0-2886.fwAlthough the filename includes "OBi110", it is also valid for OBi100 devices.
Pick up the phone attached to your OBi and dial ***1 and write down the IP address that it reads to you.
Open a web browser to that address.
Log into your OBi device. The default username and password are both admin
Click System Management-->Device Update-->Firmware Update-->Select file to update firmware.
Browse to the file you downloaded and select it.
Click the "Update" button.
You may need to re-authorize your device to use your Google account after this procedure. To do that, first, be sure that you are logged into the correct Google/Gmail account that holds your Google Voice number. Then, open another web browser tab, and log into to the OBiTALK dashboard, click on your device, then click on the Service Provider (SP1 or SP2) that is using Google Voice. Click "Accept" at the prompt. On the window that will open, click the link to "Replace Google account credentials" and follow the instructions.
I manually updated the firmware and logged into my dashboard and all is now working again.
I did not need to re-authorize my device with my Google account.