Check this link. Dell Inspiron 17 (5755 / 5758) Power Button Board with Cable - T2CVC They can notify you when it's back in stock...
Inspiron laptop 5758 bought April 2015, had power switch replaced under premium support Oct-15, 2 days after my premium support ended (July-19) power switch failed again. Replacement board (power button board T2CVC) costs between $5.90 and $15 but is out of stock on all sites I can find. DELL tell me either send my laptop in to be fixed @ $169 or to buy the small board that DELL have a monopoly on costs me $85 (Anurag Srivasava3 July 21 12:50pm ET)  This is outrageous, this is a new laptop and I'd at least expect the replacement board (oct-2015) work would be covered or DELL would at least care that I've a new DELL computer that has a hardware fault and rather then take advantage of my situation and make a huge profit they would send me a part at normal price.   
DELL demanding $80 for $5.90 part