But yes, the error occured before I updated the OS to the latest version.
I also checked SAFE MODE, and the error still happens.
I'm sorry to hear that after exhausting your DIY options, you still haven't found a fix. I'd like to commend you for your effort, well done!
Our techs at your nearest Samsung Service Center will be able to solve this issue for you. I recommend heading there to get your device fixed right!
You have two options:
1) Book an appointment through Samsung Members by tapping Support > Book an appointment.
2) Send us a message on Facebook / Twitter / Instagram (with screenshots of your post) so we can help forward you to the right care.
Hopefully you find the time to visit soon. We want to fix this for you!