Inspiron 15R 5521 Fails POST without LCD display

I have an Inspiron 15R 5521 and the built in LCD display is failing. Rather than repair it, I want to remove it and run the base attached to an external HDMI monitor. However, after unplugging the LCD connector from the motherboard, the system won't boot (8 beep code) even though the external monitor is plugged in.

Is there a way around this? A bios setting perhaps? Does anyone know if it would work if I left the connector plugged in with the cable cut rather than unplugging it?

Thanks.