S5 downgrade

[Android Central Question]

Hi I have been trying to downgrade my s5 g900t from marshmallow to lollipop and when I Odin flash it says pass on when the phone trys to reboot I just gets stuck at the T-Mobile sign and stays there I've done this a couple of times but am I doing something wrong or is it locked to where I can't downgrade I am rooted custom room and recovery I just don't like the roms they have for marshmallow

 

[Rukbat]

Are you sure you're flashing a T-Mobile S5 ROM? Normally if the phone is locked against a lower version, it just fails the flash. If Odin says Passed, it should work. But if you flash, say, a 900A ROM, it might not.