@82mhz @zhenech Could be a defective keyboard or a weirdness in the keyboard interface. If you haven't already, try booting with various likely keys held down - start with shift. If no change, try a slow tap on e.g. F10 as it boots. The first sequence could be one long beep being interrupted by the processor having other things to do. "Real" beeps are usually way slower and clearer. Like the last one (the one before the one where you turned it off). Do you get the same beeps with a warm boot as a cold one?