Here is the working solution if failed to update xhorse vvdi2 to version 7.2.6.
One of our customers tried to update vvdi2 to 7.2.6 but failed, it gave error code (6:03:A0:81) Upgrade Failed.
1.Change another USB cable or operating system (i.e Windows 7)
2. If still not working, update your Xhorse Upgrade Kit to V1.7.7, then update vvdi2 to 7.2.6