Help Please help! Phone doing custom os and unsure what that means?

[Are21]

I went to put my samsung galaxy phone in safe mode to fix an app and followed the instructions.
My phone asked me to do a custom os so i did it.
My phone is now stuck on that screen with the little android and saying 'downloading do not turn off target'.
Any suggestions how to get out of this? Im not even sure what it is. Please help?

 

[Th3M4dP1ay3r]

Pull the battery out then put it back in and do your stuff. If it happens again,repeat it.

 

[Are21]

Thankyou!

 

[Th3M4dP1ay3r]

Thankyou!

No problem man.