The Slumbering hulk- Whmr 40k horror story

2nd comapys Terminator squad Cerberus, of the Champions of humanity space marine chapter, along with a light division of kreig guardsman board a drifting battleship, dated back to the age of strife, a mechanicus ship has already boarded but gone dark, and now they're sent by their chapter master to retrieve the relic vessel and the mechanicus ship, or destroy it if the need arises...but will the lumbering giant of ages long forgotten, go quietly
*I do not own warhammer or anything like that just a free fan made story and chapter*