Go back to and enable OEM Unlocking and USB Debugging .
This is where the custom ROM community steps in. Flashing a custom ROM on this device isn't just about novelty; it is about preservation. Here is the state of the scene for the Xperia 5 III (codenamed barbet ) and why you should consider it. sony xperia 5 iii custom rom
I can provide the exact terminal commands and files you will need for your specific setup. Share public link Go back to and enable OEM Unlocking and USB Debugging