Trying to find out what's wrong with the laptop after supposed Windows 10 update?

The details of this issue are blurry simply because I wasn't present at the time of its occurrence. From what I was told, my 10 year old cousin brother attempted to update their Lenovo laptop to Windows 10 on his own and I believe the download may have failed?

Regardless of the circumstances, the above image shows up on the monitor screen display and I just want to know how we can recover use of the laptop and if it is possible to do so while saving all data and documents contained.