If you look at the motherboard inside the system case you will see the cmos battery.
located near or around it you should see a plastic jumper on the motherboard.
The plastic jumper will bridge two pins at a time.
And you should see three pins in a line.
If the jumper is bridging the two pins to the left or right where it says clr cmos
It is set to clear the cmos.
The jumper must be moved one pin over to the left or right bridging the two other pins of the three.
For normal operation of the motherboard, or the board will not post when turned on.