Sony Xperia 10 III, SFOS 4.5.0.25
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?