A major problem why the Sod did not hold is because it wasn't allowed to. Most people think they are already watering a lot but it's never too much especially when it's new sod. You have to damp it almost like a swamp and do that for at lease 2-3 weeks. You can try seeding but again you have to always keep the ground majorly wet all the time. This is the most critical stage of the process, pretty much make or brake. I would recommend roller tilling the manure into the ground, rake it evenly, apply the seed, put hay on top and cover with a fish net, then water the f@&$ out of it until you see growth then you can minimize the watering