iPhone stuck on Error 14 during update - no backup

iPhone 7 plus iOS 11.3 (I think), i went over all error 14 resolving items and no outcome.

Description and History:

The iPhone didn't have free GB. It started to turn on (stuck on the apple icon) and turn off again repeatably (I heard this is called boot loop situation).

I tried to reset him but no success. The mistake I made was to do an update via my PC. The upgrade is getting stuck on 20% and then error 14 pops up.

Reset to factory default is not an option. My mistake was i didn't back it up for 3 years and all of my baby daughter photos, videos and memories are there.

Please any advice would be help. Is it solvable ? I don't mind send it to US .