just posting a fix for support tools getting stuck at 49% and failing. as iv seen a lot of it but no answers
anyway i found this to be the only thing i could get to work on my D802T
I followed the KDZ method in this guide (thanks hyelton)
i got the correct KDZ for my phone from here: http://lg-phone-firmware.com/index.php?id_mod=36
Not sure if it has to be done but others said it helped but that is to Disable OR uninstall the LGE Modem from Device manager and set your phone to Port41
1: Put your phone in download mode by holding the Vol + and pluging in
2: Now in the select type Drop down box choose "CDMA"
3: set phone mode to "EMERGANCY_CS"
4: Select your KDZ file
5: Select "CSE Web Upgrade Test"
6: Click "Upgrade Start"
Now you should see it pass 49% this time, atleast i did