Flash to stock. getting rid of custom icon?

I originally flashed back to NCE to root my galaxy s5 (att) and installed safestrap. Then I used the extreme Debloat rom. Since then my Bluetooth and other things hadn't worked so I returned to stock. Months later now I'm having an issue with everything being really slow and when the phone goes to sleep it doesn't come back on without being reset. I need to send it back to Samsung but the custom icon is there and I can't take Ota updates. I have read the forums and none of the solutions helped. My Knox is still 0x0 so I'm good there.

I have tried:
Flashing to stock with Odin..... complete wipe
Triangle away
Something similar. Can't remember.
few other things I can't remember as its been a few months

Please don't flame me. I did indeed search and try the solutions

Again.
0x0 Knox
Custom lock icon at boot
It has been rerouted in case the solution requires root
On ANCE

Thanks for your help in advance!