[Huawei Y5 (2017) ROMs, Kernels, Recoveries, & Othe] Exconvinced:
Thanks for confirming compatibility for the MYA-L03 variant.

With regard to flashing your original proinfo file backup, it would not brick your device because it follows the same process of flashing this proinfo provided by [MENTION=6335830]salembream[/MENTION]. You can still restore back your device's original IMEI and serial number even if you unlocked the bootloader using different device's proinfo.

If you wish to retain the unlocked status of your bootloader, I suggest that you root your device now, and from there you can access the filesystem using root browser apps and manually edit the values of IMEI and serial number.

You can look up for tutorials on Google or YouTube on how to do so. I see this as a better option than flashing your original proinfo backup file as you might lock your bootloader again, unless you have you kept your personal bootloader unlock code specific for your own proinfo.

I have a request. If you have your MYA-L03 proinfo + bootloader unlock code, would you mind uploading it? I would like to try the instructions in this thread on a Y5 2017, MYA-L02 variant this time. Thanks.

---------- Post added at 05:41 PM ---------- Previous post was at 05:23 PM ----------

Based on several sources, relocking bootloader with custom ROM and recovery installed can softbrick devices, which is difficult to recover. It is understood that some of us get annoyed of the warning screen during the device's startup, but we have to deal with it because it is us who chose to unlock our devices' bootloaders anyway.

Also, it is worth noting that every after unlock or relock of bootloader, the system will immediately proceed to a data wipe, provided that the stock recovery is installed and not TWRP.

So, yeah. relocking bootloader can wipe data and can also brick your device.

Read here:

https://xdaforums.com/u11/how-to/recovering-idiocy-relocked-bootloader-t3847646/amp/

https://forums.oneplus.com/threads/...-it-cant-be-trusted-and-will-not-boot.749830/

https://forums.oneplus.com/threads/dont-lock-bootloader-after-rooting.859564/

---------- Post added at 05:51 PM ---------- Previous post was at 05:41 PM ----------

First, ensure that you have ADB drivers installed in your Windows. This allows your Android device to be recognized while in ADB or in fastboot mode. To start, kindly visit this link: https://m.youtube.com/watch?v=DPWEG3kkvXU

Once installed, boot up your device into fastboot then connect your device to your computer. Open Command Prompt (CMD) and input the following string: fastboot devices

You should see that your device is now recognized

After that, proceed with fastboot oem unlock command.

// Update //

The proinfo file also supports MYA-L02 variant.

As [MENTION=6335830]salembream[/MENTION] mentioned, you may edit the serial number written in the downloaded proinfo and change it with your device's default one. To edit, go to https://hexed.it/ and click "Open File" to upload the proinfo. Change both "R1KBBCB111111111" & "R1KBB11111111111" with your device's default serial number (written at the back of your device, usually on the battery pack). Make sure that the serial number has 16 characters. Click "Export" afterwards and proceed with flashing the new proinfo file via SPFlashTool. Although you modified the proinfo, you will still use the posted bootloader unlock command: fastboot oem unlock 5A4CB78CF6711B04.