I didn't kill it,but I did run the lawnmower at the lowest setting.It faces northeast.The thinning was either the shade of House,tree,both,orthe lack of irrigation.
Oh . Umm.. When did you lay the sod? Do you have access to a sod or grass cutter from a rental place like HomeDepot?
Big Big BIg mistake to lay sod over ANY existing grass. I am sorry to say it but if you can you need to rent a sod cutter take up all the old grass and dead material and lay the existing sod down. Decomposing of the old grass would develop an a slime, which would cause problems; also, the fact that you would have air trapped between the sod and the ground allowing the roots to dry out and die. You have to roll your yard with a large roller you fill with water from HomeDepot or a rental place. This will help eliminate air pockets and have good soil contact. You already have suboptimal growing conditions since your tifway wasnt doing well. You already have a strike against you.
My contractor laid sod over a new consruction house with mainly weeds and within 3 weeks all was dead. When you laid sod in miami did you ever go back and see what the grass looked like in 3 weeks? They actually laid sod without rolling it????We are asking you did you roll it because you can see in between lines of sod that the grass doesnt meet with the next laid piece of sod. 90% of all new lawn visitors to this site start by saying "I am in a new construction home and sod was laid BUt............!!!!!"
I would take action. I hope it turns out.
At least go up and aggressively trim the tops of your trees to give the bermuda a fighting chance.