First, try to clear the CMOS, reboot the PC to see it can boot or not.
If it does not boot after you clear the CMOS, take the cpu out to see there is any burnmark on it or not, also check the MB carefully too, because like the power was cut out when the PC is on, sometime it will cause the problem, like kill one or more pc components. If you use SSD for the boot device, it will cause of file system corruption too.