Hi Friend,you could try this command after succesful flash: fastboot boot name-of-recovery-file
then try to reboot > reboot to recovery inside the TWRP to see if its sticks...
you're welcome ^^
Thanks for your reply.
I actually tried that command right after posting here, and the returned error was something like "recovery not a complete file", which lead me to think that it was a bad download.
Tha fastboot flash recovery command did not return any error, but I guess it just did not get actually flashed. Lucky I did not f* up anything with a bad download
Long story short, redownloaded, and then all went well, running a custom rom all good :good:
Should have updated my post !