As long as you have a backed up copy of the firmware, it is very unlikely that your ASIAIR is permanently "bricked."
For the most reliable way to update firmware, try not to rely of WiFi (especially with the ASIAIR Pro).
Can you temporarily relocate the ASIAIR box near to your home network's router (or one of the mesh network's nodes, if you are on a mesh network)? You just need the ASIAIR itself and 12V power (make sure the battery is fully charged if you run off battery power), no need for cameras and mount.
If so, try to connect the ASIAIR LAN port to the router after applying power to the ASIAIR and let it boot up (probably best to connect after you hear the single beep).
Wait a minute or three and check the router to see if the ASIAIR is on the network. This will also confirm that the ASIAIR will at least boot up properly with the existing firmware.
If you don't see ASIAIR in your router's list and if the ASIAIR WiFi hotspot is also not seen by the tablet, you may need to restore a copy of the ASIAIR firmware (the one you backed by when you received the ASIAIR). The firmware will need to be at least up to v1.4 for the LAN port to work.
If the router sees the ASIAIR, try to run the new ASIAIR app with the tablet connected to your home network (make sure the tablet is not connected to the ASIAIR's hotspot).
This is probably the most solid way to update firmware. It does not depend on the iffy WiFi radio in the ASIAIR Pro.
An even more solid way to update is to directly connect the ASIAIR LAN to an Ethernet adapter on an iPad. But not many people have Ethernet adapters handy.
With the v1.5 release that just came out, it took just a second or two to transfer the firmware from an iPad pro to the ASIAIR. Installation took a bit longer. At about 12% in the install progress circle, it jumps suddenly to about 50% and a short while later, jumps to 82%, and then reporting firmware update is done an instant after that. Click on the Green confirmation button at the bottom of the update window, and you show be running the latest firmware.
I just finished updating two ASIAIR Pros that are connected through LAN to my mesh network.
Good luck,
Chen