Error during Kindle DX 2G manual updating

My Kindle DX 2nd generation (model B004) doesn’t conect to the 3G. So, I downloaded the version 2.5.8 (now it has the 2.5.6 version/firmware) to my computer and then transfered it to the Kindle DX device. Then, I disconected properly the kindle from the PC and selected the “settings” menu in the kindle and then the option “Update Your Kindle”, but it doesn’t complete the update and shows an error message. Can you help me, please?