[AC Question]

I have factory reset my old Galaxy S3 device following steps (hold volume up, home, and power keys etc) but this has resulted in an android system app called "Factory Test" appearing that runs when the device is switched on and overwrites part of the home screen with a panel that contains the device details.

I cannot disable or uninstall the app from the application manager. Is there a way this can be done without having to go into linux code on an emulator. I do not have root access to the device which would be a further hurdle.

How can i disable this unwanted display?

[B. Diddy]

Welcome to Android Central! If possible, go to Settings>Developer Options, and make sure everything there is turned off.

[MrStumpy]

Thanks for kind words B.Diddy!
Unfortunately, when I opened the Settings icon there was no "Developer Options" tab available, the 4 tabs I am able to see being "Connections", "My Device", "Accounts" and "More".
Does that mean I must go and "root" my device (for which there seem to be a number of on-line guides but if there is one you would particularly recommend then grateful for any advice).

Am hoping to be able to revive this device and give to number one son who has lost his iphone.....

[B. Diddy]

Oh, does it actually say "Factory Mode"? That can happen something called the EFS partition gets corrupted. It might be a little tricky to fix--see this video:

[MrStumpy]

Thanks - that looks feasible. Just need to root the device and I should be away!