Bootloader relock - Xperia 10 III

Sony Xperia 10 III, SFOS

My smartphone still has an open bootloader since I bought it, so I get an error message every time I start it. My attempt to close the bootloader with fastboot (“fastboot oem lock”) unfortunately resulted in the smartphone refusing further cooperation after the first start with an error message (“device is corrupt”).

I have now flashed my smartphone again and installed new software. Now, of course, the bootloader is still open and I receive a corresponding message every time I start it.

As I do not intend to install any other systems on the smartphone, I would still like to close the bootloader for security reasons. What do I have to do to make it work reliably? Do I have a factory reset again when I close the bootloader?

I suppose that there is a little misunderstanding. You are not able to lock bootloader while using SFOS. You have to live with it or go back to Android if you are feeling uncomfortable seeing such a message.

The answer should already be available if you just serach.
You can’t lock the bootloader with “unapproved” software like SFOS on it. Welcome to Android nonsense security.


I had indeed not understood that reclosing the bootloader only works on Android.

Sorry that I didn’t recognize the details. But with the new insight, I do wonder (probably with you) where exactly the security gain is for Android. Especially if the IMEI is imprinted on the SIM card tray. Then anyone really can corrupt the Android system.

I think the Sony boot OS(?) wipes your /home partition, or whatever they use, when you unlock the bootloader, hence the step in the SF installation to let the device boot after unlocking the bootloader, before you install SF.
I’ve never relocked it, but maybe it does the same again hence the unbootable state you found your device in.

I think the security gain is only legal for sony - they can say we’re not responsible