How to test camera (350d)?

How can I test my camera (xt/350d) to see if the problem I have is a camera problem or a grip problem? Wait, don't answer yet. I have also lost the original battery door for the camera so I can't put it back on to test with.

I was shooting a wedding this past weekend and the camera started acting up. I would take the picture and it would either say "Busy" forever until I turned it off or it just wouldn't take the picture (just like the camera was off). If it said busy, it wouldn't record the picture and I would have to reshoot. I know it isn't the card as it happened with 2 of them.

Before I order a new grip I want to make sure that is the problem otherwise I'll upgrade to a 40D. I don't really like that option since I recently bought the 500, but what good is it without a camera.

Thanks
Bill

Though I wouldn't say "its definitely not the grip" without testing, my first guess is that problem is unrelated to the grip. If you are comfortable with messing about DIY style there is a pin for the battery door that can be jury rigged to make the camera work without the grip to confirm.