I have a soft bricked Xiaomi phone with a locked bootloader. I haven't seen any need to unlock it, because I was fine with its OS (It is an AndroidOne phone with stock Android).
One day the phone froze while I was listening to music, and upon a forced restart, it stuck on bootloop. An issue that should have been fairly easy to fix with a reset, or at worst with a reflash of the original ROM. But turned out that I could not do any of those with a locked bootloader.
Later I've found out that Android phones have an "Emergency Download Mode" (EDL) that you can access by short-circuiting 2 test points on motherboard. Since I couldn't find a better option, I've opened my phone and tried to flash "the original", Xiaomi released ROM, but blocked yet again from doing so, because Xiaomi also locked the EDL mode. Only authorized Xiaomi personnel can flash "their" phones through EDL mode.
I didn't know any of that when I bought my phone, there was zero mention for bootloaders on user manual, EDL lock was added after a software update (which I've learned years later, as it wasn't mentioned on release notes).
So, my phone is waiting for benevolent hackers to find "exploits" in its bootloader to be usable again.
