Default [q] g2 d802 big problem

I'm not able to flash any more custom packages (rom, mod, kernel...) on my phone even with custom recovery. now every time I flash a zip file, my phone gets stuck at boot screen. I 'm not a newbie, I have been flashing phone on different brands and G2 for 3 months!
It happened after I flashed a wrong kernel version on my D802 (D800 instead). so I used LG support tool to get back to life, and the phone is fully functionnal. I can still root nd and install custom recovery, and even after flashing, I have no error message.
Any ideas?