Everything is black!

Hello. My S3000 seems to be working okay *except* that the LCD and viewfinder are black and any picture I take is black. The menu options and little icons appear, but that's it. It's as if I have the lens cap on... oh, wait!... No, that's not the problem. Can anyone help? I should admit that I took it all apart (carefully!) in order to fix the zoom error. I've checked and re-checked everything inside and I don't see the problem. Thank you for any advice you can give! :)