Ask how to restore the original OS in a few places.
1. Samsung.com
2. XDA Developers.
3. The CNET Samsung forum.
4. 1800SAMSUNG
Typically Samsung will answer for free on new, in warranty products. Out of warranty they usually tell you to arrange for service.
Bob
So I have recently bought off ebay a Samsung Note 8 and was expecting it to run like my Samsung Tab 3 and my Mum's Note 2 however when I have turned it on it runs android software in the style of a Nexus device instead of the Samsung style. This means I don't have s-note or any other similar apps which was the only real reason to buy the tablet in the first place. There are also apps which I have not previously seen on android installed. These are advanced settings, browser (not chrome as I would have expected but also not a samsung one I recognise), Dev Tools, Documents, DSP Manager, Music (not google),omni switch, supersu. I have tried a full factory reset but want to know if there is anything I can do to change it back to the samsung operating system???? Please help...

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