When i switch on my phne i get an android with a red triangle.. Why is this?

[AC Question]

I have tried factory resetting using recovery mode as well but nothing seems to work

 

[the tall guy]

Hi, were you tinkering with the phone? did you try to root the device etc?

 

[unknownme23]

Nope.. It just appeared when i switched my phone on..
it used to work normally and this red triangle appeared...
What can be the reasons?