Fail to install CM13 on Oppo Find 7a I would like to install Cyanogenmod 13 on my Oppo Find 7a.

I am following the instructions from CM wiki. I am using a laptop with Linux (LMDE2).

I fail to install a TWRP recovery. Fastboot seems to succeed (it does not print any error message). But then, when I try to boot in recovery mode, I still have the original recovery from ColorOS.
I also tried CM recovery, but then I can't even boot in recovery mode (I get stuck on the "Oppo" logo).

I tried anyway to install CM13 using the original recovery. But I get a message "Installation failed".

Do you have any idea of why it fails?



EDIT : I add details on what is happening.


When I run fastboot boot twrp.img, the fastboot screen gets brighter. But then nothing happens, it stays as is, with "fastboot" written on the screen. Then, I hard reboot my phone and hold the keys to get into recovery mode. I get the stock recovery.
When I run fastboot flash recovery twrp.img and then fastboot reboot (holding the key to get into recovery mode), the phone reboot, I get the screen with "Oppo" written, then the phone reboot a second time. For this second time, it boots in normal mode (although I was holding the special key for recovery mode).


Once I booted in normal mode, if I try to boot in recovery mode, I get the stock recovery. It seems to be expected, according to TWRP website, since some devices automatically replace the recovery mode by their own recovery mode.
I recently went through this on my Find 7 so hopefully I can help.  Here's what I've found to be foolproof.


Download the latest ColorOS software and copy it to the device's SD card (either internal or external is fine if your partitions are not unified; external otherwise).  You can also save CM13 there at this point.
Download and flash the latest stock recovery.


Extract that zip file to your current working directory on your PC, put the device into Fastboot mode (hold Power + Volume Up), and run:

fastboot flash recovery ./find7_recovery_4_4.img


Hold Power + Volume Down, releasing the former when the device vibrates and the latter after the recovery screen comes up, to boot the device straight into that recovery.
From recovery, flash ColorOS 2.1.5i and then select the option to reboot; let the device do so.
Download and flash the latest TWRP 3.x recovery: https://dl.twrp.me/find7/


Similar to (2), different filename.

Repeat (3), and you should be in TWRP and can flash CyanogenMod!