it seems you bought the G20CB model with 1pc of 230w adapter, if you attach all the port correctly means there is a problem with the cpu or the monitor. After turn on the CPU try to press capslock or numlock button on your keyboard, if the keyboard led is on, and you can shut off the Cpu by pressing the power button that means the cpu works fine, the problem might be the cable, port or the monitor.
If there is no solution you can try ask the customer support or the retailer for rma.