I updated firmware, first to 1.9.6 and after that flashed, updated again to 1.19.
Ok, that is likely the issue. If you already had a firmware version 1.14 or later, applying 1.9.6 first (which is much older) would default the panel. You would only need to apply 1.9.6 if your firmware is older than that to start with.
Unfortunately that would indeed default all settings and devices. Sensors would need to be learned back in, and Z-wave devices will need to go through the clearing and pairing process.
This thread on our support site lists out programming steps for common 2GIG Sensors. There are step by step instructions as well as tutorial videos.
For Z-wave devices (those are light switches, locks, thermostats) you would need to first Remove them. I know they are not in the panel, but that doesn’t matter, the Z-wave devices themselves save parent network data, and the Remove Device process clears that, even if the device is not actually paired in the panel.
So for Z-wave devices, go to Services > Z-wave > Wrench Icon > Installer Code > Remove Devices. Press the pair button/process on the device you want to clear, the panel will beep and display that a device was cleared, then you can clear another device. One by one clear all Z-wave devices, then go back through an add them.