Troubleshoot Want to know if my android phone is secure or the system not was altered?

[Aktiffiso]

Hi, look, my mother wants to give me one android phone, but i suspect my cousin changue the original rom or root the phone, i dont know about this things and i like you help me to know if that phone is secure because i want to use it to mobible bank

¿How can i know if the sistem was altered?
¿How to know if have the original system?
¿How to know if it has rooted?
Thanks
Really please understand me because i dont know nothing about android phones or can i download and install a clean rom. I dont know how tu use it.

 

[roger_m]

What phone is it?

 

[kylprq]

ı am using cyanogen / lineageos which not original roms with root without issues but you can flash stock firmware but we dont know which phone are you using or will use yet?