Vostro laptop model 3560 - can enter SLEEP mode WINDOWS 7 after motherboard replacement

My WINDOWS 7 PRO LAPTOP, a VOSTRO 3560 model, had a motherboard replacement with an original DELL motherboard P/N PYFNX. However, it can't select a sleep mode or hibernate since the repair. In addition, I can't connect it to an external monitor.

Any ideas how to overcome these issues?

Thank you -