Docking Station & Monitor Issues

Hi - I have a Precision 5680 and 2 Dell external monitors. They are all connected together with a Dell docking station. All worked fine...... then the monitors would not be finding a signal. I tried to disconnect and reconnect but nothing. When I closed the laptop lid - the monitors worked - when I open the lid they go black. To take a Teams call I have to use the laptop open to enable the camera and sometimes - when on Teams - the monitors will turn on based on screen sharing - when the Teams call is over it disconnects. I have a Lenovo that when I plug this into the docking station the monitors work but the Lenovo screen remains black - whether open or closed. I have no idea what to do as I need to have the monitors and the laptop all working as a 3 screen set-up. Anyone have any ideas? many thanks.