Iphone 4s boot loop problem after upgrading 8.4

After upgrading my iPhone 4s to 8.4, it has been into boot loop without be possible to stop it. Further to many efforts and software re-install, i found that problem focused on restoring of the back up. When restore it and set up as new iPhone all had been in normal operation. Although, later after hard reset and restore and set up iPhone using back up either from iCloud or iTunes, same boot loop problem has been raised.

Could you please advise how it is possible to stop boot loop problem without losing my data?

iphone is not jail breaking.