How to install TWRP if usb device not recognised? I am able to list my Redmi Note from cmd via fastboot devices on Windows 10.

But I want to flash the latest TWRP on my old HTC One XL. I am able to get it recognised by adb devices. Then I can to to fastboot via adb reboot bootloader. But then fastboot devices returns nothing. 

Windows complains that USB device was not recognised 

I do have the latest platform-tools



I did install the latest HTC Sync Manager. HTC One XL is not listed there as supported though.

Q1) Any idea how to make fastboot work? 

Q2) or even better how to flash the latest TWRP to HTC One XL? I got TWRP 2.8.4.0 already there
Since you already have a version of TWRP flashed and working, you can use it to flash your new recovery image without the aid of a PC. 

Boot into TWRP, select Install and follow the screenshots for the rest.

(Click an image to enlarge it)





If you know where the recovery partition corresponds to under /dev, you can also use TWRP's command-line feature.