Fix #1: Remove the batteries from the camera, wait a few minutes. Put a fresh set of batteries back in (preferably rechargeable NiMH 2500mah or better) and turn the camera on. If that didn't work, try pressing and holding the Function or OK button while turning the camera on. Fix #2: If the camera's batteries ran down completely while the its lens was still open, the camera may show a lens error or not start properly when new batteries are installed. Remove the memory card and keep it removed, then install the new batteries. When you turn the camera on with the card removed it may come back to life, as this triggers a reset in some cameras. Error E30 (for older Canon's) means that you don't have a memory card installed, so turn it off, slip in the SD card and turn it on one last time
Answers & Comments
Try one of these two fixes, if they dont work for you follow the link below for further troubleshooting.
http://camerarepair.blogspot.com/2007/12/fixing-lens-error-on-digital-camera.html
Fix #1: Remove the batteries from the camera, wait a few minutes. Put a fresh set of batteries back in (preferably rechargeable NiMH 2500mah or better) and turn the camera on. If that didn't work, try pressing and holding the Function or OK button while turning the camera on.
Fix #2: If the camera's batteries ran down completely while the its lens was still open, the camera may show a lens error or not start properly when new batteries are installed. Remove the memory card and keep it removed, then install the new batteries. When you turn the camera on with the card removed it may come back to life, as this triggers a reset in some cameras. Error E30 (for older Canon's) means that you don't have a memory card installed, so turn it off, slip in the SD card and turn it on one last time