Hi,
Verify that you have the good update for your device : version + vendor.
Check the SDcard's filesystem, remove all file before, better format it. But be careful, there is a standard way to format a SDcard. Take a common size for the SDcard : 4, 8; 18 GB.
Make a full charge of the device, reset the device, shut-down it properly. And try again with your fresh SDcard and the update file : put only the zip file on the SDcard, don't unzip it.