Macintosh HD isn't visible in Disk Utility after trying to update OS X
Hello, I have some serious issue with my 15" Macbook Pro late 2013 i7 2.3, and I'm looking for help. I've attached all screenshots that could be helpful and I mention them in my post:
Everything was fine with my laptop until I finally decided to update my OS from El Capitan to Mojave. After my computer rebooted and started installation process, an error appeared that said there is no disk to install new system. I opened recovery mode with command + R, and disk utility showed only Apple disk image with OS X Base System, that has 1,3GB (screenshot #1). My main Macintosh HD 500GB drive was not visible. Therefore I couldn't reinstall OS X by myself. I Googled some solutions, runned 'fsck' in a single mode (screenshot #2). I reseted PRAM and SMC but nothing helped. So I took my laptop to service point where technician formatted my disk and checked if it is damaged. His diagnose was that disk is fine, but EFI is corrupted and he suggest replacing a whole motherboard. I decided to take my laptop back home for now and try to look for less radical option.
And now... A plot twist! What changed after visit in service point. When I run my laptop in normal mode turning on the power button, a blinking folder icon with a question mark appears. When I run in command + R Internet recovery mode, there's some new stuff happening: my 500GB HD disk is now visible for a while in Disk Utility! (screenshot #3 & #4). But when I try to verify or repair disk, I get errors (screenshot #5 & #6), and after that disk dissapears from the list on left side of the screen. It's only visible shortly after opening the Recovery Mode for a first time. Same thing happens when I'm running Terminal as first thing and type 'diskutil list', it's visible (screenshot #7). But when I exit Terminal and try that again, it dissapears.
Please, help me, did that guy from service was right and there is nothing else I can do than just replacing a whole motherboard? Or there is some hope? I'm not a very technical person, but I appreciate every hints and help!
Ist dies eine gute Frage?