Help Failed to unlock bootloader using fastboot tool

[CoolShark]

my GN repeatedly auto-reboot, I don't know what is going on, probably, a kernel service is broken.
I tried to unlock bootloader in fastboot mode using fastboot tool.
fastboot oem unlock
below is the printed message:
F:\i9250\platform-tools>fastboot oem unlock
...
OKAY [ 21.025s]
finished. total time: 21.025s

the phone indicated the bootloader was unlocked, and status was okay.
after unlock, the phone didn't self reboot.
however, I restarted phone or restarted bootloader, it was still locked.

the original system version was 4.0.4, a couple of months later, it was automatically updated to 4.2.1.
I checked the module versions, as follows:
bootloader: PRIMELA03 (it was old version in 4.0.4)
baseband: I9250xxLH1 (the new version in 4.2.1)
Linux kernel 4.2.1

how to correctly unlock the bootloader?

 

[HangoverDanny]

Hello,

I have the same problem. My son´ s GN repeatedly auto-reboot. I can not do anything with the phone when it is on. Only on for 20 sec and then reboots again, i can't change any setting or do a factory reset.

I have used every program i could find. Every time i unlock the phone he is locked again when the bootloader restart.

I have used 2 programs at once, so i can unlock the phone while the other program tries to flash the phone. The program flashed the phone, it took 30 minutes, replacing the system , userdata etc, but when the phone was turned on again everthing was still there.

I can not do factory reset with the phone and via the bootloader menu nothing changes.

Greetz Danny.