Error 21 again

[useriphone5]

Hello friends!
I need help! If you can (any hint help).

Windows 7 iPhone 5 - updated itunes - original cables - updated pc drives.

I will summarize ... I forgot my iphone at home and it all discharged one day there tried to reload and he was the apple looping.
I tried to restore it in DFU mode, and also in recovery mode, but the two modes show the error 21 and can not proceed with the installation of ios.
I had this problem a few months ago in the same cases and managed to fix it.
I found that the error 21 was appearing for the moment it will install on the iphone ios, he was disconnecting the device ... and to successfully achieve the installation, the device can not disconnect. So it was back to go to restoration screen or dfu (however had already disconnected). And so the error 21.
In the first time I gave this error very researched and several people said it was the battery. But I kept trying to fix yourself at home. and got even without changing the battery. I confess I do not remember in detail what I did because I was so excited when I could not pay attention.

I remember a friend said to try using TinyUmbrella, and uncheck the option "set hosts to Cydia on Exit" But this option in Advanced, can not remember if it was possible to be check or uncheck. But I was able to make the itunes restore my iphone is that first time! When installing iPhone NOT disconnected and the installation was normal .. it worked several months ..

Finally, now again I have the same problem. Error 21, for cases discharged completely.
Anyone have any tips? A program (I do not know), to avoid the iPhone restart during the installation ???
Help guys .. to several days trying to solve ... Thanks!

 

[useriphone5]

no one????

=/

 

[Just_Me_D]

According to Apple:

If you see error 53, learn what to do. If you see one of the errors below, you might have a hardware issue:
1, 3, 10, 11, 12, 13, 14, 16
20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 56
1002, 1004, 1011, 1012, 1014, 1667 1669
Here's what to check:
Make sure that you have the latest version of iTunes.
Check for issues with third-party security software.
Make sure that your USB cable, computer, and network are reliable. Then try twice more to restore your iPhone, iPad, or iPod.
If you still see the error message, you can check for outdated or modified software or contact Apple Support.

Check for outdated or modified software

If you see error 1015 or a message that says, "The required resource can't be found," your device might have unauthorized iOS modifications ("jailbreaking"). Or you might be trying to install an earlier version of iOS (downgrading).
Update to the latest version of iTunes, then use recovery mode to restore your device to the latest version of iOS.
If you still see an error message, contact Apple Support.

Source: https://support.apple.com/en-us/HT204770