Sony Xperia 10 Plus bootloader unlock fails

Hi, happy new year! : )
i bought a used Xperia 10 Plus (dual SIM) with Android 10 and wanted to install Sailfish on it. But i am unable to unlock the bootloader as described in your guide: jolla[DOT]com/install-sailfish-x-xperia-10-windows/

my current setup:
PC: Windows 10 Pro / version 1909 / OS build18363.1198
phone: Xperia 10 Plus / dual SIM / I4213 / Android 10 (i know this needs to get downgraded)

What i tried so far:

Try #1) Unlock bootloader with sailfish package

  • downloaded sailfish OS *.zip and unpacked
  • checked *#*#7378423#*#* for bootloader status: equals YES
  • connected phone with fastboot (blue LED)
  • set up drivers from Sailfish_OS-Jolla-3.4.0.24-i4213-0.0.4.10.zip
  • opened CMD
  • [CMD] checking fastboot availability with fastboot devices: device is listed!
  • [CMD] executing bootloader unlock

    fastboot oem unlock 0x4DF*************
    FAILED (remote: ‘Command did not succeed’)
    fastboot: error: Command failed

Try #2) Unlock bootloader with general Sony instructions from here, hoping that the Sailfish tools are just incompatible due to the android version: developer.sony[DOT]com/develop/open-devices/get-started/unlock-bootloader/how-to-unlock-bootloader/

  • removed previously installed drivers
  • downloaded and unpacked platform tools “platform-tools_r30.0.5-windows”
  • downloaded and unpacked USB drivers
    • Sony sends me to Google’s page which wants me to download OEM drivers: developer.android[DOT]com/studio/run/oem-usb
    • this redirects back to Sony’s dev page: developer.sony[DOT]com/develop/drivers/
    • there are only drivers for Sony Xperia 10 II listed, so i chose them - no clue if that’s correct : /
  • checked *#*#7378423#*#* for bootloader status: equals YES
  • connected phone with fastboot (blue LED)
  • set up drivers from Xperia_10_II_Driver.zip
  • device now recognized in Windows as “Sony sa0200 ADB Interface Driver”
  • opened CMD
  • [CMD] checking fastboot availability with fastboot devices: device is listed!
  • [CMD] executing bootloader unlock

    fastboot oem unlock 0x4DF*************
    FAILED (remote: ‘Command did not succeed’)
    fastboot: error: Command failed

So, with both procedures the unlock was just unsuccessful without any hint at what is actually going wrong. I definitely need some advice here, because i just can’t find any answers with Google that help me resolve this. If i understand this issue correctly: As long as the bootloader isn’t unlocked, i won’t be able to use the Emma FlashTool in order to downgrade to Android 9.

Do you guys have any ideas that i could try? I bought that Xperia for the sole purpose of flashing Sailfish onto it. And i don’t know how closely Sony and Jolla are cooperating but the provided guides are … quite disappointing. If there’s a way to provide feedback regarding that i would really like to do that : )

Looking forward to your suggestions.

Edit: improving formatting

Exactly same experience on used XA2

Sony Xperia XA2 unable to unlock bootloader (again)

Installing Sailfish X on Sony XA2 that had a locked sim

Thanks for your response, deloptes.

i came across these articles before. The reseller originally stated that the device was without branding and locks and if there is one it is not visible through the interface. But to be sure i sent the reseller an e-mail asking specifically for this. i hope they have an answer.

i gotta say, that i’m disappointed by this : / i mean, the Xperia devices are officially listed as supported Sailfish-devices and then you find out that that’s not really true. And if what deloptes linked is true, then Jolla should probably make clear to their corporate partners that bootloader locks shouldn’t be a thing, at all, if they make a deal. After all, they are improving the Sailfish OS to be more user friendly and all but in order to make it work you need far too much technical expertise in the first place and then your efforts might be in vain, anyway /sigh

Will try within the next days again, hoping that some of you still have a smart solution. If all fails, maybe i’m lucky to at least get the money back for the phone. i assume, i won’t get a refund on the 50 EUR license, though …

I can’t recall the exact details, but can you make sure you have an internet connection when you flip the “OEM unlocking” toggle under “Developer options”? I can’t remember if the toggle was greyed out or if the fastboot oem unlock simply wouldn’t work, but I recall spending a lot of time trying to get the unlock process to work, only to find that having a Wi-Fi connection while flipping the OEM unlocking toggle was the key.

I had no interest in connecting the phone to the internet since it was already at the Android version that was needed, and so it didn’t occur to me to try connecting to the internet until that was pretty much the last thing I could think to try.

Although this resource concerns XA2 it shows the same sort of chain of issues, which were eventually resolved for OP: https://www.reddit.com/r/LineageOS/comments/apa2cu/sony_xperia_xa2_bootloader_unlock_fails/
I would have a look at Flashtool as contains all necessary drivers: http://www.flashtool.net/downloads.php

Whilst not a Windows user by choice, I have a couple of laptops one running Windows 10 Pro Build 18362.19h1_release.19318-1202 and older one Windows 8.1 Pro Build 9600 to fall back upon which has Sony sa015, sa018 and latest sa0200 ADB Interface Driver(s) installed. I might add in both cases these laptops have USB2 not USB3.

Lastly you don’t need Emma to flash stock ROM to downgrade as both Androxyde Flashtool and Newflasher can achieve this result.

@jprostco raises an interesting point as usually unlock after trying both cellular and WiFi connection under Android first.

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