New Used Surface Pro 3: How2check for Malicious Stuff seller MayHave installed?

Spelling Correction: Malicious - Couldn't figure out how to edit Subject or Delete my post and start over. Sorry. Content below:

Mod Edit:  Fixed - Hamluis.

I just bought a Used Surface Pro 3 from a guy on Craigslist.

He had worked in the computer field.

When the deal was done I left feeling uneasy about what he may have  put on the Microsoft Surface  Pro 3 I had just bought from him.

He said he had done a fresh Windows 10 install on the machine.

I started wondering what else he had installed... maybe something to capture my accounts and passwords... I'm unsure.

Windows Security reports all OK except it "flags"

.. Virus & Threat Protection - it wants me to setup a OneDrive account.

.. Account Protection - It wants me to sign in with Microsoft

These also show up on my Win 10 desktop.

Question 1: How can I check the Surface Pro 3 with Win 10 to see if the seller installed any kind of spyware or key tracking or other malicious stuff?

Question 2: Must I get a Microsoft account and setup a OneDrive account to get Windows Security Full Protection?

Thanks for any help.

Edited by hamluis, 05 March 2021 - 10:26 AM.
Moved from W10 Discussion to Tablets/Surface - Hamluis.

Hi,yes. you,ll  need to sign in to microsoft,to use Onedrive,..although you dont need onedrive for anything to do with system security..all you really need is the built in windows defender..guide below

https://www.windowscentral.com/beginners-guide-windows-security-windows-10

..guide below,if you want to use onedrive..

https://www.windowscentral.com/how-get-started-onedrive-windows-10

I wouldnt be too paranoid about the vendor putting anything on your laptop,..im using a secondhand system,..although bought from a friend i trust,..after it had been through a computer shaop i trust,..

on the other hand,..its nice to have peace of mind,...

Ultimatelly to be 100 percent sure theres nothing on your system,you could, re install windows,..or "reset", it,which is actually fairly easy,and totally reliable, on win 10..

Then you would start with a totally new clean system..

If you want to do that  you go to "Settings",-Update and Security - click on"Recovery,on the top left - then click on"Reset This pc" - then "remove files and clean my drive",..(remember to back up,into a usb,any files you really want to keep,beforehand,..

Straghtforeward guide here..

https://www.laptopmag.com/uk/articles/reset-windows-10-pc

Hope some of this helps,..let us know if you have any further questions..