[Help] Weird freezes and shutdowns (flashed Stock)

[mudderz]

Lets see i can can get help here- xda 70+ views no comments :[
So i have a galaxy s5, was running Cyanogenmod 12

my phone was freezing and rebooting then eventually it was stuck and would only boot into download mode
so i cut my losses and flashed stock 4.2 and 5.1.1 (files from samMobile matched model number) and the problems persist

cleared cache and factory reset multiple times and booting in safe mode doesn't fix anything

the phone freezes on samsung splash screen usually mid animation, sometimes i get to tmobile screen when it freezes.
sometimes it will boot without any problems and work normally for a few seconds then freeze and shut off into the same loop

i have searched and can't find any advice past (flash stock and your good )
oh and knox counter 0X1 (2) so no warranty for this guy.

i decided to see what it would do in TWRP and the device reboots while in twrp while trying to flash anything or formatting but navigating menus is fine.

i just got a Security Error: this phone has been flashed with unauthorized software & is locked. etc

 

[ironass]

Lets see i can can get help here- xda 70+ views no comments :[
So i have a galaxy s5, was running Cyanogenmod 12

my phone was freezing and rebooting then eventually it was stuck and would only boot into download mode
so i cut my losses and flashed stock 4.2 and 5.1.1 (files from samMobile matched model number) and the problems persist

cleared cache and factory reset multiple times and booting in safe mode doesn't fix anything

the phone freezes on samsung splash screen usually mid animation, sometimes i get to tmobile screen when it freezes.
sometimes it will boot without any problems and work normally for a few seconds then freeze and shut off into the same loop

i have searched and can't find any advice past (flash stock and your good )
oh and knox counter 0X1 (2) so no warranty for this guy.

i decided to see what it would do in TWRP and the device reboots while in twrp while trying to flash anything or formatting but navigating menus is fine.

i just got a Security Error: this phone has been flashed with unauthorized software & is locked. etc

Hello and welcome to Android Central mudderz!

Did you follow best practice and make a nandroid backup prior to installing CM12? If so, you can use that to revert back.

Does the phone boot if you first remove your external SD card?

 

[mudderz]

no backup. and sd card or no sd card still freezes

 

[ironass]

no backup. and sd card or no sd card still freezes

Can I just check that you are flashing the correct stock firmware for your model of Galaxy S5. I assume from your initial post that you have the T-Mobile (USA) model and not a T-Mobile international version. Also, bear in mind that T-Mobile (USA) has 2 Galaxy S5 models... G900T & G900T3

 

[mudderz]

It's the SM-G900T

 

[mudderz]

I restored with kies and it still in boot loop

 

[ironass]

I restored with kies and it still in boot loop

Did you do a FULL WIPE+FACTORY DATA RESET and then check your device before re-installing any apps, as per #2.3, #2.4 and #2.5 of S5 Lollipop Update Problems - Dummies Guide. If not, try that.