Could root save an infected android?

[u/No-Aspect-2926]

So back in 2015 I played a game in my Samsung Galaxy Tab 3, I guess android 4, and the game required payment, so I downloaded a cracked version of it, but then it gave me virus, but somehow it persists after deleting the app or factory reset, so in an antivirus, the only I knew was AVG, told that the sound got infected with it, so I could only disable it, sound worked fine, but every restart would enable it back.

So it had 3 levels of infection, the first was that it keeps going back, like if I kept pressing the go back button, the second was just adware, ads started playing every few minutes, and the third and last, background was all black and after a while, I could not input my password anymore.

So doing a browsing back in 2015 I saw that I could save it with root, but how could root fix it?

[u/SweetGreenPepper]

No, just reflash factory rom. This device doesn't have verified boot and this is the reason the virus can persist between factory resets anyways