Samsung Galaxy S5 unroot/Unbrick not woring

[AC Question]

So im just going to explain what happened. Originally i rooted my samsung galaxy s5 g900a with towelroot, and i got some rooting programs. It went fine for a while but then there was an at&t update, and i accidently updated it(please dont ask how), and I did, and eversince then i couldnt acess google play, it said no connection, so I tried logging in and out of my account, and then it wouldnt let me log in to my account. So i reset my phone did so much stuff and still wouldnt work. I couldnt even re-root it or anything, and it said it was not rooted, so i just tried to root it everyday. Today it worked rooting, and i rooted it and then deleted the hosts file for freedom which fixed me being able to login in to my google account, but google play still said no connection so i tried everything it said to fix it with no avail. Then i tried reinstalling the firmware, but odin just wont work, i can install the stock kernal but not the rom. I am sure I have it right. So then with safe strap i tried to reinstall the firmware with, but it still didnt work, so i tried reseting, but i went reset the data cache and something else, which i am pretty sure was the os. Now i can put it into download mode, or recovery mode, and i also cant install the firmware with recovery mode, but anything past that it keep showing the Samsung start screen and shows a unlocked lock and says custom, but wont go past there. This whole time whenever i try odin i just says fail. I have no idea what to do know, i am pretty sure i just bricked my phone, and if i could get it unbricked, i would also like to know how i can fix the google play no connection, i have tried everything i have found online so far, so this is my last resort, and my only hope please help.