I think I messed up with Twi5sted Lollipop

As in the title I think I messed up when I installed Twi5sted Lollipop; the phone shows the following:

• Model Number: SM-G900T (Here I guess is where I messed up because afaik T is for TMobile while I should have A for AT&T)


• Android Version: 5.0


• Baseband: G900AUCU3BOC4


• Kernel: 3.4.0-4432708


• Build Number: Twi5ted Lollipop V-7

The phone has lost root and I cannot use Flashfire to install another ROM.

Is there any way to downgrade to stock ROM and then be able to root/flashfire again?