Black screen surshot camera

The camera has a recall issue, it's called a CCD sensor. Your problem is better known as the black screen of death. To date Canon is the only company that will repair this issue for free, Call Canon and they will send you a shipping label that you can print out on your computer and send them the camera and they will fix it and send it back free of charge. Canon has excellent customer support, I would never purchase any other brand of camera other than Canon because of the lack of other companies not standing behind product repair issues that are a result of poor design flaws on parts.

This sounds very much like a defective CCD imager. If so, Canon should fix this for you for free, including free shipping both ways. This is regardless of your camera's warranty status. Please check the following two links for more info:
　
http://camerarepair.blogspot.com/2007/11/canon-digital-cameras-showing-black.html

And this applies worldwide. For the UK and your A70:
http://www.canon.co.uk/Support/Consumer_Products/products/cameras/Digital_Compact/Powershot_A_series/PowerShot_A70.aspx?type=important&faqtcmuri=tcm:14-522149

Click on the "Service & Repair" link in the left column of the above link to find the nearest service center to you. Make sure that you make it very clear to this service center that your submitting your camera for evaluation and free repair under the CCD advisory.　

Applicable cameras include:
A40, A60, A70, A75, A80, A85, A95, A300, A310, S1 IS, S60, S200, S230, S330, S400, S410, S500, SD100, SD110, IXUS V2/300/400/430/500, IXY Digital 200a/300a/400/450/500