It started with not being able to open a file , after several attempts of reboot. It even tried to auto diagnose but just waiting.The absolute biggest culprit I have faced in my IT life is hardware failures. Most notably, hard drive failures. The advent of SSD has aleviated that to a certain degree, but the technology is still expensive in comparison to conventional rotating platters.
Depending on what has failed, it is difficult to diagnose without a lot more info.
I can get to bios.