TheOpSys

If you just want an easy workaround, you could try Brightness Slider app. Otherwise, follow @black.dragon74's suggestion. Good luck!

Maybe someone can help this guy @lucasdessy with he's problem...

Well, you were right @Jake Lo, it was layout id 28, I might have modified somehow AppleALC.kext, prior to all these trials. I've reinstalled macOS to refresh the kexts and now it works. Also user @hus2020 pointed me that he used (for his X260) @tluck's guide for Lenovo T460 and by following that guide I was able to get my X260 working as it should, with everything working, except SD card reader. Thanks and good luck!

Yes I did, I'm going to try again by deleting all involved kexts.

I already did, but with no results. Something else might not be right... also the camera is not working (not even shown up in System Info) , although my USB ports works well and on other similar laptops (T460, which is similar) seem's to be working.

ScreenShots:

I've tried, but with no success, still no sound available with AppleALC, only works with VoodooHDA, but with the problem I mentioned above.

Thanks @Hervé for your suggestions, I finally managed to install 10.13 on it, with MBR patch method by @crazybirdy. QE/CI is working on Intel HD520 with injected ID, Lilu, IntelGraphicsFixup and RehabMan's Clover DVMT patch, LAN is working, Audio is working with VoodooHDA (but every time I restart the laptop, the output device switches to Line Out, instead of staying on Speakers), Brightness is working, but still no Wake from Sleep and no Wi-Fi (the device had an Intel M.2 NGFF adapter and seem's that Broadcom's alternative for this kind of slot/dimension is pretty expensive and/or hard to find), I thing I'm going to get a dongle and sacrifice a USB slot for Wi-Fi.

Thanks, I agree that the solution is to use the MBR patch, but the problem is, in my specific situation: the approach that I have to apply, in order to do that. I have no option for an USB stick to do the job.

So, I'm in the following situation: a few days ago I got a X260 (i3 6100U) which have SPV lock on BIOS, meaning that I can only boot from internal SDD and I can only make some specific changes on it. Ok, the thing is that almost all the settings in BIOS are compatible with macOS, except the fact that the Bios is in Legacy mode, which doesn't allow me to boot from a GPT partitioned SDD. If the SDD is MBR partitioned (two partitions, one FAT32 for Clover and the other one HFS+J), I can reach the High Sierra Installer with no problems, but I can't install it on the HFS+J partition(due to MBR). Do you guys have any suggestions on this one? Thanks

For audio try VoodooHDA, but for LAN I have no idea...

Yes, the internet over the cable is working. For Wi-Fi and Bluetooth, I changed the native adapter with an Atheros 9285 and changed the BIOS with 1.40 modded version.

Try using this kext AppleIntelHDGraphicsFB.kext.zip. If still not working, try to patch the last working kext, from previous working hacks you used on your laptop by replacing: \/ this: FABA00600009BF006000040F44FA09F7 with: FABA00600008BF006000040F44FA09F7 /\ LE: Oh, and by the way, if you used my EFI-to reach installer files, it is very important that after you installed macOS on your HDD and installed the video kext, to replace the bootloader content with EFI - Post Install files (in your case, delete DSDT and SSDT's from ACPI\patched from the pack), because the first EFI-to reach Installer files/options will block the QE\CI (I used a FakeID to trick the installation, that's why we don't have to delete the graphic kexts from the installer).

I have High Sierra installed on my device for about a month now, but I didn't get any 'Supplemental Update', the only official update coming from AppStore, as I said, was the iTunes one and my macOS High Sierra version is 10.13.

Until now, only iTunes updated for me, I didn't get any other updates from AppStore. If you can reach the OS, but you don't have QE/CI, just reinstall the video kext, if you can't reach the OS, use the USB stick with the EFI-to reach installer to boot into macOS and reinstall the graphics kext.