I have multiple tp-link wifi extenders at home. This RE705X is the best of them.

I have upgraded my 5G router recently (tp-link) and I had to reset all the extenders to use the new wifi. Each extender showed an firmware-update message so I updated all of them without any interruption from my side. All went good, except for this RE705X which went into an infinite reboot loop (reset button didn't help).

I contacted support via email and we went through multiple steps of troubleshooting that ended by this email: issue confirmed kindly contact seller and claim your warranty 
 

The seller, after few days, replied that the device is out of warranty.

Feeling unsatisfied as the update wasn't supposed to brick the device and it wasn't my fault, I kept chatting with AI which convinced me that we can fix it. I ended up wiring the device through UART hoping to flash the firmware from U-boot. I was able to load the firmware I downloaded from this page https://www.tp-link.com/uk/support/download/re705x/v1/#Firmware to the RAM. However, just before flashing the AI warned me this firmware is supposed to be loaded only from the web interface and only, and we must use another binary file to be used specifically through UART.

So  my question is how to obtain this firmware binary?