See also: Part Orders, Open a Line Item, Open Line Item from System Menu OR Tool bar OR Part Order Header, Open Flagged LI
Steps:
On the Quick Access Tool bar (appears
on the left hand side of 'Title bar' of the application), click 
Open Object button.
On the Open Object dialog box, from
the Object drop down, select 
Part
Order Detail.
In the ID field, enter the ID of the Part Order Line Item that you want to open. The Line Item opens.