Only come on when power chord plugs in then turns back off.

Hi @patriciagarrard

Disconnect the power to the PC and then open it up and remove the RTC coin cell battery from the motherboard and then press and hold the PC's Power button for a full 30 seconds and then release. Note: Check the orientation of the battery before removing it from the battery holder on the board. Usually it is +ve on top as seen on the battery.

Whilst the battery is out measure its voltage. If it is<2.4V DC replace it. The battery model number is printed on the battery itself. Usually it's a CR2032 which is commonly available e.g. supermarkets. If you don't have a voltmeter then if the battery is >5 years old replace it anyway.

The battery is a non rechargeable Lithium type battery and it usually lasts for 4-6 years. Its function is to maintain the BIOS settings when the power is turned off and if it gets too low the BIOS can become corrupted preventing a normal start.

You may find that when you have reinserted the battery (check that the orientation of the battery is as before) and reassemble the PC that when you turn it on, there may be a message saying the the date and time are incorrect. This is normal as the BIOS has been reset back to its factory default condition. Once the date and time have been adjusted, the message won't appear the next time that the PC is started.

Here's the system battery replacement procedure from the user manual that may help.