2000 4Runner limited

It grinds when trying to engage from 2WD to 4H and into 4L. Grinds and eventually you can slame it into gear(I only did that once, I didn’t keep trying). Does it when the trans is in any gear, P, N, D etc, vehicle parked. Know that it’s an auction vehicle that I just bought, I don’t know the history, when it last worked or what might have happened. The 4WD light doesn’t come on at all. The light doesn’t come on when engaging it electronically either. I already swapped the fluid in it along with all the vehicle's fluids. Anyone have a step by step troubleshooting guide? Thank you

 

It is a certainty that you can shift it without grinding with the engine shut off.

 

Kind of sounds like the transmission might be having issues, might be stuck in a gear. Does it drive normally backward/forward, shifting through the gears?