troubleshooting – Nikon D7500 with 18-140mm kit lens

I’m new to dslr cameras, as i love photography, i decided to get a Nikon d7500 with 18-140mm kit lens.
I’ve just mounted the lens to the camera but when i see through the viewfinder, the image doesn’t look bright and seems like the lens or the sensor is dirty, i already checked the camera and lens they are brand new. i haven’t put battery yet, could someone please tell me if this is a problem or just because i haven’t inserted a battery yet ?
Thanks in advance