Seeding needs to be done in the next couple weeks around here so I imagine you're even on a tighter deadline.
Seed needs to make contact with soil and be wet thats all it needs to grow. Seed that sits on the top of thatch or dead grass laying over will not grow. I would check to see if the sod is actually rooted. If it died out before the roots took I would just roll it up and throw it away and seed on the old soil. If it is rooted scalp it with a push mower and just rough up whats left. I seeded my front yard last thursday I have sprinklers coming on every two hours for 10 minutes and its keeping it just about ideal moist and we've been in the mid 80s for highs. Good luck!