Hello,
I have purchased an Xperia 10 III from an online source. It is labelled NTT Docomo on the back, so I believe this is unlocked from Japan.
I successfully entered developer mode and went to find the boot-loader. I ran into “bootloader unlocked: no”
Is it possible to change this to Yes, so I can flash the device?
you USED to be able to do this with the S1 qUnlockTool bootloader unlocker. you would pay $20 or so for a credit from one of the folks selling server time, run it, and it would work its magic. i did it to four docomo-branded xperia devices.
however, the places i bought the credits from don’t sell them anymore, apparently, so maybe it is not possible
edit: this is the thread that i started out from https://xdaforums.com/t/closed-bootloader-unlock-allowed-no-to-yes-is-now-finally-possible.4044091/ way back in the distant past
5 Likes
Check the official install instructions and you’ll find official Sony way to unlock it for free.
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Read all of it, please:
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are you guys SURE you know what you’re talking about?
i believe the OP is not talking about just unlocking the bootloader, which is easy to do using sony website and fastboot, after checking OEM unlocking.
my comments are about removing the carrier-specific bootloader-unlock-restriction that, as far as i know, is present for sony xperia models ONLY on japanese-branded, docomo-carrier phones.
this restriction results in Bootloader Unlock Allowed: no in the service info menu:
- android dialer => dial
*#*#7378423#*#*=> Service info => Configuration => Rooting Status
this absolutely prevents fastboot from unlocking the bootloader, with or without the sony code, and with or without oem-unlocking enabled. the only way to remove that is with some computationally intensive cracking that you used to have to use the S1 unlocking tool to do, and as far as i know, is now impossible.
@Chranah, if you dial that code in the dialer, go to service info/config/rooting, do you see Bootloader Unlock Allowed: no if it actually says yes, then this should be easy.
ALSO, its possible this is somehow different for the 10 III. maybe docomo stopped with the unlock-restriction. the last device i had to do this for was a docomo-branded XZ2 compact.
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You are right. If the carrier has prevented unlocking the bootloader, then our instructions cannot help. I misunderstood the original question.
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Can the firmare be changed with Xperifirm? I remember that you could flash different versions of official vendored images on the Xperia X back in the day.
@rozgwi
Although of no help to OP in this thread as bootloader can’t be unlocked, yes it is possible to flash Global firmware to a “Docomo” device using Newflasher although due to different hardware (frequency limitations) there maybe issues.
the problem is not the docomo-branded android firmware image, its that the bootloader is locked and cannot be unlocked. if the user could flash other firmware, the problem would already not exist.
@ teleshoes, you are correct, and you stated what I was attempting to say in a much better way. I went through all of the steps to get into the menu, including * android dialer => dial *#*#7378423#*#* => Service info => Configuration => Rooting Status
The end result is
I had read about the S1 tool, but also saw that it had been removed from every site, including XDA, I searched. (maybe because it wasn’t entirely legal)
I am finding no way to contact Docomo other than calling (I can’t find an email or contact form) and even then, what I’m asking isn’t a common thing they deal with. I think returning the phone might be the only option at this point?
Thank you all for your support up to this point! 
it is the only option i know about, unfortunately. good louck