Why Always fail to update my mobile phone software.
You should charge your phone to at least 70% before attempting to do an update. The last thing you want is running out of battery while it is doing the update and bricking your phone.
If you are comfortable in doing this yourself, have you tried the manual route by downloading the firmware here:
Once you have downloaded the firmware, just place thezip file in the root directory of Internal Storage. The phone should detect the package.
If you don't feel comfortable, then you should wait for the next update. This was the last time I heard about an issue with the FOTA and the best course of action is to wait.