How to restore/edit build.prop after rebooting (and phone stuck in reboot loop)?

Question

I was trying to setup a custom host name for my device(a rooted xperia z) following this guide but without paying too much attention, especially to the comments.

I'm guessing I had a typo in the edited build.prop file because after I rebooted the phone was stuck in a boot loop: I would see the sony logo but instead of the usual xperia logo and colourful boot animation the phone would restart.

I can turn off the phone and I think I've managed to get it in a different state by pressing the volume up key multiple times after powering up because I could see a blue led always on. Before that in between boots I would see a red led blink twice.

Unfortunately the phone reboots to fast to become visible to adb. What are my options on restoring/editing the build.prop file ? Can I somehow see the phone's filesystem on a computer without booting the phone into android ? Also I don't mind loosing all the data as long as I can use the phone again.

Thanks

Answer 1

After a lot of reading and trying various things I've managed to get control over my phone again.

This guide sounds good, but it didn't work for me as I've encountered an error because of my specific device. This might work with others though.

What worked was this guide(which has problems rendering images sometimes). I've tried first to unlock the bootloader(BLU button in Flashtool) and used the these instructions to obtain the unlock code based on the IMEI. After that I've downloaded a stock FTF image (from goo.im), placed in the firmware folder of Flashtool. Then I could flash the FTF to the phone. Also, because I was using Windows 8, had to reboot into trouble shoot more to change an option to allow non signed drivers.

Hope this helps others with similar issues.

Answer 2

Wow. I was just going to say fastboot flash recovery openrecovery-yourversionTWRP.img from the terminal if you can figure out the device's specific button press sequence to boot into stock recovery or fastboot mode. From TWRP you can change file permissions if needed, and flash SuperSU, BusyBox, and if needed also CF-Autoroot if your phone is compatible. All this info is easily found on YouTube a lot of the time as well if you'd like a video to walk you through it.

You might also just try to flash a boot.img from a stock version before anything in case it's just the kernel. FYI, if you can get a custom recovery onto your phone like TWRP, you can back up EVERYTHING once its working again for safe keeping in case something like this happens in the future. Just run a once over NANDROID backup and you're set.