Hello Andy and welcome to the forum! 🙂 Battery warning in the M7 is flashing LEDs. Dead batteries are indicated by bc in the display or the display disappears altogether.
It seems from the manual that there are no downward pointing triangular LEDs in the display, so I'm not sure what you mean when you describe a "red down led".
Just in case you have the camera set to DX and no film in it, try this: Set the film speed dial on the back of the camera to anything other than DX - say 400ASA. Turn the shutter speed dial to AUTO. Make sure there is a lens on the camera and take the lens cap off. Make sure the camera is switched on - turn the little lever at the front of the film wind lever so that it covers the small red dot. Wind the film wind lever so that the camera is cocked. Look through the viewfinder and press the shutter down a bit. You should see a number appear in the bottom of the viewfinder, it will be either flashing or solid. The number is the shutter speed the camera has selected for the aperture on your lens, if it's flashing you need to adjust your aperture until the number stops flashing.
Hope this helps.