Let's just recap.
You have 4 CN cameras that are bricked, with at least one by upgrading to the 5.4.41 firmware.
That triggers the 'downgrade block' Catch-22 scenario.
So, to recover and do the proper upgrade, the steps are as follows:
Use the Brick-fix tool via the Hikvision
tftp updater. This only needs to be done once. It does its work on the first reboot after install, all this does is make the camera able to be downgraded. No services are active, so the camera will not (for the first 10 mins anyway) appear in SADP, no web access, no SSH, no telnet. It appears to be inert.
The camera is now ready to take the '5.3.0 to 5.2.5 downgrader' via the tftp updater. There is a CN and an EN version depending on what language the camera presents as.
The camera will now have a normal web GUI, probably in Chinese.
At this point either the 'classic mtd hack' can be done, to convert to English, or the 'enhanced mtd hack' to convert to English and be fully upgradeable.