Can i demand that sprint store give me a new phone?

i went in last week to see if my phone that had some technical damage to be fixed. the phone was still functional, however it kept turning off every 15 minutes. i got my phone back from the technician and now my phone doesnt even turn on and all my contact and important data is still on it. this is ridiculous, i want to demand them return my phone to its previous state or give me a new one.