I installed the CHDK menu on my G5X (thy for the explanations with the wiki 
) but after going to Disable LCD off : Always it's still the same thing.... it turns off after few seconds. Anybody have a solution please ?
There have been some previous reports of disable LCD off not working correctly in conjunction with HDMI out, see
https://chdk.setepontos.com/index.php?topic=13993.0 for discussion and some possible workarounds.
However, based on the following question, you should also verify that CHDK is actually running when you see this behavior. If CHDK isn't loaded, then obviously the setting will have no effect.
Another question about the CHDK menu, do I have to install the ''new'' firmware every time I want to go to the CHDK menu ? Because if I close the menu, then I can't have access to it anymore... I have to install again the firmware.
There's two different things that may be getting mixed up here: Is CHDK loaded, and how you access the menu.
There are two ways to run CHDK on your camera
1) The "firmware update" method, where you start the camera, go through the Canon menu, and select "firm update". This runs CHDK
once, and if you restart the camera, CHDK will no longer be running, unless you go through the "firm update" process.
2) "Bootable SD card" method. With this method, you prepare the card in way makes the camera load CHDK every time it's turned on. See
https://chdk.fandom.com/wiki/Prepare_your_SD_cardOnce CHDK is started by either of these methods (you'll know by seeing the CHDK splash screen), pressing the "alt" key enters a mode where you can access the CHDK menu and adjust CHDK settings. Pressing the "alt" key again leaves alt mode, but CHDK is still running. By default, the alt button is the "mobile connection" key.
