I have a 8320 and Im using DM 4.7 and I am unable to upgrade my OS. Here are the steps i've followed;
1. downloaded an installed new software
2. deleted vendor file
3. connected 8320 to pc
4. opened DM
5. DM scans for update
6. DM says update is available
7. i click 'update now'
8. dm goes through a 3-step check series. the last step it 'communicates with device'
9. DM tell me that there are no updates available ???
I believe DM 4.7 will re-install the vendor.xml file when it checks for updates so you might want to check to see if it showed back up and re-delete it then disable your internet connection before running DM.
Or just do what savioAMG suggested
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Hotchanna, as you can see, a lot of your issues seem to be caused by DM 4.7, which also causes a lot of issues for others. I'd recommend just downgrading to DM 4.6 which is less buggy and seems to work almost 100% of the time.