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I have just rooted the LG Optimus 4X HD using instructions I found at How to root the LG Optimus 4X (LG-P880)?

I now need to unlock the bootloader, but for some reason the command adb reboot oem-unlock does't seem to do what it should. All it does is reboot the device, and it boots normally again. Apparently it should boot to a screen asking if I want to unlock the bootloader.

Any ideas why this is not working for me?

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That was my post (actually, with the JB update, rooting got even easier) – so maybe I can help you a second time:

Initial note:

IMPORTANT: Unlocking the bootloader on the O4X only works with Firmware V20 (approved for V20A and V20B; as OP hjust upgraded using the official tools, most likely V20C works as well). To check what firmware you're on, go to Settings › About Phone › Software Information – last entry there should read "Software version", starting with "P880XXY". If XX is a 20, you're fine; if it's a 10, you'll need to upgrade your device first.

Official approach

XDA Developers has a post describing the procedure. Requirements are similar to the ones in my "rooting answer", so you should already meet them. According to that "official LG procedure", the steps are as follows:

  1. fully charge your device to 100%
  2. connect your phone in LG software mode (or simply enable )
  3. run: adb reboot oem-unlock

Alternative approach #1

As that failed for you (and not only you, others report that as well), let's look for an alternative approach. In another thread, XDA features an unlock tool for our O4X. I just found this now when looking for a different post – and wondered about the "relock" part: AFAIK, the O4X uses FUSEs for the lock status. Once blown, there's no way back. Obviously, that XDA member found a way around that (using a boot-loader hack): "by using this program you have 16 chances to unlock relock bootloader before all fuses blown".

Alternative approach #2

That's rather a "last resort" if everything else fails: Blow all the related FUSEs directly. Again described in an XDA thread (note the original/initial post has some errors, so here's a corrected version):

  1. open a terminal (or use adb shell)
  2. make yourself root (run su)
  3. get the actual FUSE state by executing cat /sys/firmware/fuse/odm_reserved > /data/local/tmp/odm_reserved
  4. in the created file, change the line 0x000000000000000000000000000000000000000000000000 00000040000000c8
  5. write it back: cat /data/local/tmp/odm_reserved > /sys/firmware/fuse/odm_reserved

While this directly blows the FUSEs, it has one advantage over the "official method": No data lost, as no is performed – a fact it most likely shares with "alternative approach #1" ;)

Check results

Whatever approach you took: You can check the results in "Hidden Menu" (dial 3845#*880#).

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  • i should have also mentioned, in the hidden menu there is no bootloader status option
    – chenks
    Dec 12, 2014 at 17:26
  • I've just checked: It is there ("Bootloader Unlock Check"). May I ask which firmware version you're on? I'm afraid all the above is only valid for v20 – not having the entry in HiddenMenu points to a v10 firmware.
    – Izzy ♦
    Dec 12, 2014 at 19:25
  • I'll need to check in Monday as I don't have the device with me now. Where do I check?
    – chenks
    Dec 12, 2014 at 22:51
  • Settings › About Phone › Software information should reveal it. Last entry there should be "Software version", starting with "P880XXY". If the XX is a 20, you're fine – if it's a 10, you'd first need to upgrade. Another indicator: Which Android version is it running? v10 = 4.0.3, v20 = 4.1.2. In hindsight: If my rooting answer worked for you, your device is most likely still running v10...
    – Izzy ♦
    Dec 12, 2014 at 22:58
  • android 4.0.3 LG-P880-V10h-NOV-19-2012
    – chenks
    Dec 15, 2014 at 7:37

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