Can't restore (bricked?) router: Image uploading failed. The selected file contains an illegal image

Hello to all,
I am unable to restore firmware on my DVA-5592 from the recovery mode (in normal mode it only power on and ethernet is not even active).
Whatever firmware I try to restore I always end up with the message stated in the title.
In the Recovery page there is an option to write misc partition. If I enable such option (1, 2 or 3) I get the following:
"New software is being programmed to the flash memory. The Router will reboot upon completion. This process will take about 2 minutes."
Problem is that it never reboot.
In all the cases seems to be that the firmware is successfully uploaded to the router (ethernet led start and stop blinking once done).

I have no idea on what could be the problem and I'm surprised to see that things get stuck in this way without any log message.

The firmware is OpemWrt and provided by D-Link (download links to the end).
The router specs are:
Broadcom BCM63136B0
armv7 Cortex-A9 (ARM Cortex A9 Dual Core: 1000MHz)
Total Memory: 256MB

How I ended up with what seems to be a bricked device?
I suspect this happened during the firmware upgrades/downgrades. Mamy times, for unknown reasons, I never got to the result page. Depending frome the browser (Firefox, Edge, etc) I always got problems like no reboot, browser crashes, stuck on waiting, connection reset etc and I have been forced to power off-on each time. Firmware has always been restored and working even in such way except this time.
I always restored the firmware by using an AndroidTv device connected to the router through its ethernet port (unfortunately my PC got broken during the operations and I had to continue in this way).

As of now, I'm trying the restoral process in this way:
an old DD-WRT router connected to DVA-5592 via ethernet cable. To access the recovery page (192.168.1.1 for this type of router) I join the network by connecting to the old router through Wifi from a tablet running Windows 10 (I only have USB or Wifi here). Whether I connect in this way or directly through the AndroidTv device the failures are more or less the same.

One last thing...
Given the above problems I was wondering if I could try to install a full official OpenWrt firmware. Although I don't see my exact model on the list, there is one for D-Link DVA-G3810BN/TL which has nearly the same specs. I don't necessarily needs all features (for example, I don't have a Fiber connection, so everything related is useless).

Thanks to all

Firmware links:
https://media.dlink.eu/support/products/dva/dva-5592/driver_software/dva-5592_a1_wi_20191219.zip
https://media.dlink.eu/products/DVA-5592/DVA-5592_A1_WI_20180823.zip
https://media.dlink.eu/support/products/dva/dva-5592/driver_software/dva-5592_a1_wi_20180405.zip
Recovery page:

this device doesn't appear to be supported by openwrt, what would you like us to do ?

Openwrt was not involved in your mishaps?