I had a problem updating my computer from the High Sierra to Mojave. It crashed midway and would not start again.
I brought it to the Apple Store. During the meeting with Genius, he constantly looked at the phone and was very brief with his answers.
He explained that all my data had been deleted, this was while he was on the disk tool, which showed a full blue bar. Anyone using a mac means that the storage is full. He said that there is nothing to do and that I should delete and reinstall the operating system.
He said he has been working there for 6 years and this was his solution? I know I should have backed up my data and even warn you to back up before upgrading. I won't make that mistake again. But this employee couldn't care about my computer and my fault.