Help how to update firmware

[GrandViken]

So new user here, i have a galaxy S5 from At&t that i got from walmart a year ago. I unlocked it and switched to tmobile, i want to know how to update the firmware on it since kies says i have the latest firmware, and through the phone settings it still tries to use the at&t network to search for updates...im using a custom apn for tmobile since it initially didnt connect. I want to update to 5.0 if possible, if not...what can i do?

running android 4.4.4
model - G900AUCU2AOA1

 

[ironass]

So new user here, i have a galaxy S5 from At&t that i got from walmart a year ago. I unlocked it and switched to tmobile, i want to know how to update the firmware on it since kies says i have the latest firmware, and through the phone settings it still tries to use the at&t network to search for updates...im using a custom apn for tmobile since it initially didnt connect. I want to update to 5.0 if possible, if not...what can i do?

running android 4.4.4
model - G900AUCU2AOA1

See #1.6 of 40 Galaxy S5 models - Dummies Guide. You have a non Samsung firmware carrier variant and need to be on the AT&T network to update. Best suggestion is that you borrow an AT&T sim card or get a PAYG one, to receive their update.