Help! I attempt to lock my screen and it doesn't work

[Android Central Question]

Hey; I have a Samsung Galaxy S3 (Mini) and I recently just erased ALL the data off it since it had some bits and bobs from when I last used it.

So, I go to turn it on sleep by pressing the powerbutton for 1 second and it doesn't turn off,

before you suggest; Yes! I did you a third party app; swipe-to-lock, assistive touch and many more.

 

[B. Diddy]

Welcome to Android Central! Does it work properly in Safe Mode? https://support.t-mobile.com/docs/DOC-32821. If so, then something you installed is causing the issue -- you'd have to uninstall apps one by one until the problem goes away.