I wasn't standing behind you, watching everything you did, so I don't know what happened. Somehow, something you did triggered the update to 5110, and then something else triggered the update to the default version, 4972. It's possible that Obihai actually pulled that 5110 build, since it had bugs, but I have no way to know.
I wouldn't worry about it at this time.
There are four ways that a firmware build can be written to the device:
1) You manually download a build from the "Firmware" section of this forum, and then manually upload it via the OBi device's local (embedded) web server. To do this, you need physical access to the device so you can log into its IP address.
2) You press ***6 on the device to check for a firmware update. The system compares your device's firmware build to the build it thinks you should be using, and, if it decides you need an update, it tells you that one is available, and tells you to press 1 to accept it. This method will typically give you whatever build Obihai considers stable, which may not be the very latest.
3) You configure a service via OBiTALK portal that requires new firmware to enable that service or feature. Obihai will then automatically push the required build to your device and reboot it. This is what might have triggered the 5110 push to your device, if you were looking at the new OBiEXTRAs offering. Google Voice is another example; some old devices had firmware incompatible with Google's new authentication protocol, so OBiTALK would detect that and push the required build.
4) OBiTALK can periodically check the firmware build of your device and push a new build, if one is needed. This was a controversial topic a few years ago, but either they've stopped doing this, or, they've only been doing it rarely, to fix a critical bug, as nobody has mentioned it recently. It hasn't caused any problems for several years.