Ye updating with Sony software won't work nor the over the air update. But that's about it as I've seen.
But I remember on my Sony Xperia V that when I relocked it, then I could use Sony update again and I did so wiping everything before I sent that one to the repair shop. They repaired it and I got it back. All under warranty
The latest update .757 is really buggy, hope they fix it. Phone restarts sometimes when using the camera.
Sent from my C6903 using xda app-developers app
Xperia Z1 - Stock kernel - .761 - Locked Bootloader
Xperia V - New display and working like a charm.