i have a EOS T6. I recently purchased a 30d for the 28-135 lens. I got it fairly cheap so i don't expect it to be perfect. But one of the problems i keep having is the orang flashing light in various light conditions. I now know it means slow shutter speed. In manual mode that makes sense and i have kinda started to figure it out. but it happens all the time in auto mode as well. When i get it in auto mode i have switched to manual mode, and changed the shutter speed so it will take a picture and then immediately go back to auto mode and now it works. I have other lenses and i have only had this problem if i forget to turn auto focus off when taking pictures of the stars at night. Is there a trick i am missing?
It could just be unable to achieve AF. If something more serious, I doubt the 30D is a good candidate for repair. If you have a local camera store take it in and have them check it out. If not maybe you can return it.
The 28-135mm zoom seems an odd choice to photograph stars.
If you intend to do astro work you really need to be in all manual control anyway. A lens like the Rokinon 14mm f/2.8 IF ED UMC Lens is a great choice. It has a reasonably fast constant aperture and is fully manual. You could make some stunning shots with a properly working 30D and the Rokinon. Best of all the Rokinon isn't expensive. 😊