Trying to factory reset galaxy, wierd thing happens
What button combination are u using and there should be a factory reset in the setting 

Go to settings
Scroll to backup and restore click it
 scroll down and there should be a factory reset button 
I'll probably have to have 30% or more battery  to do so 

I have not had that model of phone but I've had a few Samsung's if  above is not possible u can use Odin mode  and flash new firmware to the device it's very easy to do if u have a PC to do it with 
Look for ur model phone and Odin guide 
Here is one I looked up for u 
Delete the space before and after the word firmware

http:// firmwarefile .com/samsung-sgh-t959