OnePlus One - How to enable USB Debugging with broken TWRP My device is Oneplus One, I installed Android 7.0 on it, then I installed OxygenOS 3.1.3. Then I thought to get back to CyanogenMod 13.0 with SultanXDA 3.4.0 kernel.

I've got bootloop, but I still don't know why.

I've noticed that my TWRP version was 3.0.3.2 (by Tugopower) so I wanted to reinstall it using the original TWRP recovery 3.0.2.0 image.

I installed TWRP successfully and pressed Reboot -> Recovery but after that I can't get access to TWRP anymore.

Fastboot says that USB Debugging is disabled.

How can I enable USB Debugging in this situation?
You don't need debugging mode to flash. You must boot in bootloader (Fastboot mode) and flash the files.

This tutorial explains clearly the whole process. You need the second method since you are not able to boot in recovery mode.