fermentation stopped way too early... dead yeast?

hey guys, got a fermentation problem here.

this is my 3rd brew, the first two i used dry yeast and everything worked perfect. this is my first time using liquid yeast and my fermentation stopped way early. i'm using white labs yeast, i cant remember the type, it was california ale yest maybe? anyway, my buddy and i brewed last friday and OG was 1.048. seven days later the gravity is only 1.040. i thought the yeast may be dead, but would there be any fermentaion at all if it was dead? ferm temp has been aound 75. my friend did forget to put the yeast in the fridge when he got it, so it sat at room temp for about 5 days. any suggestions? thanks for your help.

Gently swirl or stir the yeast sediment on the bottom of the fermenter, being sure to not oxygenate the wort. If it does not kick back in to high gear, repitch a new vial of yeast. If you still have problems with new yeast, the wort was probobly not well aerated (which yeast needs to replicate before they start converting sugar into alcohol) hence the stuck fermentation. Next time be sure to aerate the wort very well, and have a yeast starter prepared a few days before brew day. A yeast starter will boost the pitching rate, as well as indicate a yeast problem before it is added to the wort. And of course keep the yeast refrigerated untill a few hours before use.

I say leave everythign closed up so as to avoid infection. Order ( or go to LHBS) and get some new yeast and pitch that.
Should be all good.