Booting up with blinking crossed circle and Apple logo.

Hi, I’m ALEARCHIS. My MacBook Pro mid 2012 model A1278 running MacOS Sierra 10.12.8 with a ROM 4GB and 240GB SATA SSD. The computer was operating fine not until I installed The latest macOS Catalina on it. Though it was still operating at it’s peak with the macOS Catalina, I later installed Logic Pro 10.8.4. But still the computer was operating fine with software. No System delays especially when I’m Working on my music projects. It was really working fine ,but All of a sudden one day I was working on my music project Then I decided to delete one of the folders from the music software Boom that’s where the Problem begins, it took like 30mins deleting the folder , my MacBook Pro could not respond to commands eg the trackpad can’t give feedback . Nothing the computer is just stacked! I had to force shutdown by pressing the power key for 10 seconds then switch it on again, after process the computer was booting up with a blinking crossed circle and Apple logo, I tried to reinstall the macOS mountain X lion but all didn’t work. I tried to Erase the SSD and run repair on it but it keeps on telling me error messages needs repair . so I had to cleanup the motherboard , remove Rom And the RAM then disconnect the battery from The computer and connect it back Then reinstall the macOS Sierra again, surprisingly it was able to install and now the computer is working fine but it cannot allow me to restart it. Once I restart the computer, booting up is a problem unless I have to force switch off and then switch it on again. But if I shut it down as usual , it boots up without any problems. The problem is that I should not restart the computer! So what can I do?