I don't know, but I can tell you how to. Make a back-up, wipe your phone with bbsak, uninstall new os and install old os, open loader exe and load the installed os, then restore your data.
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what works for me is, if its not a verizon OS, I delete the vendor xml and empty my trashbin too from the computer. Then I go ahead and disconnect from the internet and just plug in my phone and open up BBDM. Also like what abtjason said make sure you uninstall the OS and install the OS that you want to load on your phone. Hope this helps.
