Perhaps this has already been said. But for those upgrading the firmware of the DMM6500. If your 6500 currently has a version less than 1.7.10, consider doing what I did and first install 1.7.10. You need to use the "downgrade" button to perform that update. Then, after 1.7.10 is installed, use the "upgrade" button to install the latest version - 1.7.12 as I write this.
In my case, my DMM6500 had 1.7.5 installed. So I downloaded both 1.7.10 and 1.7.12 from the Tek website. First installed 1.7.10 using the "downgrade" button, then installed 1.7.12 using the "upgrade" button. Why? So that the firmware version displays correctly. Doing it this way avoids that annoying bug where only 1.7.1 is displayed.