P20 mainboard weird issues

[arvacon]

Hi. I had reboots issues with my old mainboard, so I decided to order one from Aliexpress, as I found one with more ram and rom (6/128 instead of 4/64 I had before).
I installed it and I found that the bootloader must be locked, so I can not install any rom. In the menu, the update choice is missing too. When I connect it to pc, Hisuite can't detect it, whatever I tried, as at the device manager it shows as USB composite device and not as android adb device. I installed a lot of drivers, different versions of hisuite, but without success, so I can't continue the installation of Hisuite proxy procedure. I tried run commands via fastboot, but it can't write tprw, it always says failed.

The weird thing is, that the device shows at its menu that it is the EML-L29 C432 model, but when you search the imei on the ime******.com, it shows that this imei belongs to chinese version EML-AL00C, so I think this must has been rebranded. Also when you boot in fastboot mode, it shows that it is unlocked, but when you run fastboot commands or other tools, it says that bootloader is locked. The seller was claimed that this is an unlocked board and that's why I bought it. Is it possible to have install a bootloader that shows faked unlock message? Also the phone is not rooted and it has Huawei erecovery installed.

Another issue that I found, is that DC unlocker shows different IMEI than it should be, I don't understand why...

I feel a little confused now. If I pay to unlock it and try to install a rom, which one should I install, the European or the Chinese? Which one should I install to not make it brick, should I continue treat it as EML-L29 or as EML-AL00C? Also if I have to install finally the chinese one, does this means that my sim card networks will have any issues afterwards?

What is the right order to make this phone install the latest android version or even Harmony, without become bricked? Until now, I have make it to boot in test point service mode as the backcover is still open, so is there any way I can install twrp or any rom, without need to search and pay for unlocking code?

What is really going with this board finally?
Which steps I should follow? Where should I start?

[arvacon]

I forgot to mentioned, that I tried the PotatoNV, and for some reason it chooses automatically the bootloader as kirin 620. Also once at the device manager it showed the device as Hi3650 (Kirin 950) too. Is it possible they have load a wrong bootloader, so that is why Hisuite and windows can't see the device correctly? The weird is, that windows explorer can see the phone as storage and the cd hisuite part too, and you can transfer files normally, although only when you disable HDB setting first, so windows can see it then as portable device normally.
When you boot into fastboot, device manager shows it as kedacom usb device, but if I boot in erecovery mode, it shows as usb composite device that it can't start.

I hope these info give you the picture of what I deal with...

ps: I attached a fastboot cmd commands photo too.