[OnePlus 3T Questions & Answers] GammarursPulex:
Girlfriend here: Whoever said that having a break and eat something before going back to some PC problem was right xD

Ok, what i did now:

First i deactivated the automatic Windows-Update (not sure if there was the problem, but i had some problems with this automatically-Winstupid-Stuff... doesn't matter..).

Then i connected the op3t with the volume-up-trick to the computer and i got the "RELINK HS-USB QDLOADER 9008" back in the DeviceManager. Now i deinstalled the DeviceSoftware and like you said (maybe i was blind before...) there was a checkbox unlocked. I locked it (said something like "deleting DeviceSoftware from PC" or something like that) and clicked on "OK" to deinstall the DeviceSoftware.

I interrupted the "automatical installing drivers" in the Popup what shows at the right side of the task-line (i only got ~3-5 seconds until it was finished, so i had to do this step 2 times until i was fast enough^^). Windows said now that there was no success in downloading/installing the DeviceSoftware. Finally!

Next step (now i had enough time, because Windows didn't download/install anything) was right-click on the "QHUSB_BULK" and finally could install the downloaded drivers. DeviceManager now shows a "Qualcomm HS-USB QDLoader 9008 (COM3)" at "Connections (COM & LPT)".

I started the MsmDownloadTool aaaaand got Sahara-Error :D

Tryed another run with changed properties (compatibility mode (Win XP, SP3) and gave AdminRights). Now it shows me "Start Download Firehose Binary" and then returns to the "Sahara Communication Failed"-msg. Glad i found lyall29's post at page 6. Needed to make the whole thing 4 times until this error was gone >_<

When the download started, the op3t got a.. not sure, yellow? maybe lightgreen? LED-signal during the download is now running.

Until i wait:

Maybe the first mistake i also had was:

When pressing the power-button for 40 seconds, the op3t has to be turned off at the end. Then wait some seconds. Then push the volume-up for 10 seconds and then while still pushing the volume-button, connect the op3t with the computer to get the msg at DeviceManager.

Nvm, after the download finished, i got another popup sais "unknown device" and that Windows couldn't install the DeviceSoftware.

I did "Step 9: Disconnect phone from PC and boot into system." aaaaaaaaaaand.... it worked. Q,Q

Now all i need to do is trying to get the backup back until my boyfriend is home :D

But one question is still open:

When we tryed to load the backup, then the op3t said, that the backup is encrypted. But.. i'm pretty sure we didn't encrypt the phone-data. We also thing, that the problem why the backup didn't work correctly was, that the data was encrypted and so we couldn't gain access to it. We tryed this with his Win7-PC and my Linux-Laptop. Even with different USB-Ports (2.0 and 3.0).

I'm going to do a new backup now from the op3t, but what if the problem shows up again?

Someone got an idea if the MD5-Backup-Stuff should be encrypted or decrypted? :confused:

Besides that:

Thank you very much for the help!! I guess i wasnt that qualified with fixing phone-issues and i might did some very nooby failures... so really thank you for your patience :D