recover data from unbootable phone with broken touch

[Kadyn]

My Oneplus3 touch screen stopped working yesterday. I did some googling and was told that erasing cache through fastboot could be a solution so I did using.

fastboot erase cache

Now my phone just hangs on the boot screen when trying to boot into android...

I can still get into TWRP and connect through adb I would like to create a backup with:

adb backup --twrp

but I'm just greeted with the message

Now unlock your device and confirm the backup operation...

which of course isn't possible without using the touch screen.

Any ideas on how I could recover data?

Edit: I feel like I could get a long way by repairing the cache partition, which would enable me to boot to android and use a USB-OTG mouse or something. Not sure how to do it though.

[irl]

TWRP adb backup is started immediately, no confirmation needed. You can ignore that message and check backup.ab file is growing

fastboot erase cache

will erase the file system from partition. what you want is

fastboot format:ext4 cache

that will allow you to boot to android and use a USB-OTG mouse