POS Ingenico alert irruption
If there is power to the SCP, you should see a lit LED in the top-left hand corner.
If not, then it is a power issue. Check your power supply and the powerbar or outlet it is plugged in to.
If there is a lit LED, then chances are the board-level battery is dead. It's a button-style battery. You can not replace it yourself.
You will need to contact Ingenico or the company that sold it to you, to arrange for them to replace this battery.
Any attempt to open the SCP will most likely result in completely disabling the SCP, requiring it to be sent to Ingenico for repair.