Ps4 beeps 3 times at power up?

As already mentioned in title above, my Ps4 beeps 3 times fast at the start. Danch does nothing.

Previously, she stood in my room for a while without use… The only thing I have turned off is the power cord, because I can't find the original

It may be that you come to the other button, the one for the disc. If none is in, the ps4 beeps 3x fast.