Use this:
http://caftp.3owl.com/File_Upload_Admin/Files/build.prop
It will be in there temporarily so tell me when you have got the file or I will delete it at some point.
You may want to modify it since my device was in the UK and it is using release5a.
Next time try creating a backup, it uses your time for a reason.
If you want to backup in /system/ then you can copy the file in the directory renamed so you can just remove a character or something from the backup file to get it in use also you do need to delete the failed one or if you don't have one then find a way to get in and do it but you can't use ADB in recovery unless you have the release1a recovery.
If I did backup, my device is soft bricked, rooted and have such recovery then what I would do is:
cd /system/
su
rm build.prop
mv build.prop.bak build.prop
EDIT: You have till the 25th before the file gets removed from my website.
Sent from my Sony Tablet S using xda premium