The usual region which results in the message on the device screen "(System) Software Missing" is region 14 (0x0C) which contains the data from fw_all.bin. Unfortunately, neither Updater nor WU specify the problem region when displaying that generic message of being unable to flash the requested region.

Let's try to flash only fw_all.bin without the other minor content of the firmware file (minus regions 249, 251 and 253). Same procedure using Updater, after extracting the ZIP drag the reduced 074502000780.rgn onto Updater.exe, etc.: [Only registered and activated users can see links. ]

NOTE: Everything we try is at your sole risk. There is no risk at all as far as i can tell in flashing an individual region separately in a 'soft-bricked' but otherwise-healthy device and i've done so innumerable times with various types of Garmin devices over many years. However, i don't have access to a 696 to pre-test anything i suggest to you here. There is also the very real possibility that your device has a failing flash chip where there's physical damage to flash blocks which contain an essential region or regions... in much the same way a USB stick or SD card fails. If that's the case then it could fail completely at any time and of course flashing it places additional stress on it so it may even die during a flashing attempt. I'm sure you understand that and will proceed only on such condition. Rest assured i won't suggest trying anything i wouldn't do myself if the device was mine. IMHO it's worth making every possible attempt to revive it as these 695/696 units still sell for US$1000 plus in good working condition.