OK, thank you very much for your help and sorry for the trouble...
I'll PM you.
Maybe DarylUK could do the same test (he had the same kernel panic) ?

I just tried with the screen completely unsoldered, it's the same result : pi shutdowns completely, powerboost stays powered. I found a multimeter and without power plugged and switch off : resistance value is moving a few seconds and stabilizing around 1.9 M ohms. Far not between 500 and 1000 ohms....

I re-soldered keep-on on pin 8.
Yes, when I short the two grey wires, it powers off the powerboost

IMG_20161010_221638.jpg IMG_20161010_221748.jpg IMG_20161010_221717.jpg Safe shutdown switch 3.3V to pin 17 on pi second wire from 3.3V to pin 11 as asked before Shut-off to pin 13 on pi Low bat not connected as asked before Keep-on not connected as asked before LBO not connected as asked before EN...

I un-soldered keep-on from pin 8 : after shuting down, both screen and powerboost stay powered.

I just wanted to use hdmi. But I had problems last week-end, trying to shorten this cable. So I'm now using the composite cable. I didn't update my build, I first want to resolve a few problems first.

When EmulationStation is launched, nothing happens. I push the switch off : power off without kernel panic, screen staying powered. I push the switch on, nothing more.

ps : I still have LBO and low_batt removed, keep-on on pin 8, and config.txt line commented. That's right ?

I removed both LBO and low_batt : after complete loading of EmulationStation, I see the video "Warning battery very low" with the countdown, then the pi powers off (with the screen staying powered as before). I also tried moving the switch from on to off during the video, nothing happens. I tried wi...

OK, I'll do this tonight (I'm at work now). Thank you for your patience.

I've soldered the keep-on on pin 8, and removed line in config.txt. When pushing the switch to off, pi powers off without kernel panic. It's completely off after a few seconds, no led blinking on it. But screen stays powered. Then I push the switch to position "on", nothing happens.