I’ve found a way to convert the ES to a US model!
Now all I need is a working dump from a US unit and a similar ES unit.
You flash the US dump onto the ES and you end up with a US clone.
I’ve also sorted out the A12 error.
I’m currently in the process of resolving the issue of changing the MAC addresses and serial numbers on these units.
...

@dizzyadam
Thank you very much for the files. They clarified the situation with my equipment. Both files worked on my US-48-750W. I have the 750W model, but they are absolutely identical in terms of hardware, i.e. they have the same boards, and the only difference is in the slightly different power supplies. The dump from ES worked without any problems. After flashing the dump on the programmer, I reset the settings using the button and configured it as a new device. The dump from US also worked, but, as expected, returned error A12.
(By the way, I am currently working on a solution...

At first glance, there could be two issues here: hardware or software.
I'm leaning toward the latter.
In the very first millisecond when the processor wakes from reset, it reads the state of certain pins on the board. These are called straps. They physically determine: base bus frequency, memory type (DDR3/DDR4).,boot order (SPI Flash, NAND, etc.).
Sometimes, the base memory configuration, if the board design allows for it. And most importantly, the vendor! (For example, Samsung or Micron). If you had a Samsung, for example, and you installed a Micron, this is exactly what will...

In your case, you need to connect to it via UART. You can use a service cable, or if you don't have one, you can use any USB-Com converter. This will allow you to see the boot process. Open the terminal, and when the device boot lines start running, you need to press Ctrl-A on the keyboard. This command will start an internal recalibration of the RAM timings, called SHMOO. The process may take a minute or a minute and a half. After that, it will write the new calibration to the flash....

Try pressing Ctrl-Z.

Oops... I completely forgot that you have an Edge Switch and not a Unifi Switch...
Actually, the dump is still very important for me even if it's an EdgeSwitch! The hardware is identical, and I can compare the EEPROM structure. To get to the Linux shell, please try typing "start shell" or "system shell" from that menu you saw. Once you see the $ or # prompt, the dd command will work.
If "start shell" doesn't work, no worries! You can get all the info I need directly from the CLI. Please run these commands and paste the output:
"show version"...

Thanks for your help!
Just copy and paste these three commands; it's the easiest way:
dd if=/dev/mtd0 of=/tmp/full_dump.bin
cat /etc/board.info > /tmp/board.txt
cat /var/run/board.id >> /tmp/board.id
Download the files: You can use WinSCP (for Windows) or the scp command to download the file from /tmp/full_dump.bin, board.txt, or board.id on the switch to your computer.
Thanks again!...

Hi dizzyadam,

I’m currently repairing the same model and doing low-level hardware/firmware debugging. To continue, I’m looking for a full raw SPI flash dump (32MB) from a working US-48 or ES-48 500 (750)W for comparison purposes.

The dump can be made safely from Linux via SSH, read-only, without disassembling the device or risking it.

If you’re willing to share it, it would help a lot. The dump would be used only for repair and research, not for redistribution.

Thanks in advance....