Same! Mine is still not working after I woke it up from sleep yesterday. Troubleshooting and even workarounds i found online have not helped. LEDs are still on, but keys do nothing. External keyboard plugs in and works fine. Plz fix!

+1, Keyboard didn't work after waking up from sleep yesterday. External keyboard still works.

You may try to delete the redundant keyboard layouts in the Alienware Command Center application. Download and update the Keyboard firmware using the Keyboard Firmware Update Utility available for this product from Dell's "Drivers & Downloads" webpage.

I've done that already. Also it had shown multiple keyboards, one being the working one. But now only the non working keyboard is visible in awcc.

does the keyboard show up in awcc?

Update = An agent arranged for the depot repair service for this m15 R4. Awaiting conclusion.

Just received my laptop after repair. The keyboard works, by replacing the main logic board. However, the AWCC does not recognize any of the rgbs on the laptop, nothing is shown. Also, my powersupply just doesn't work. This is honestly one of the most frustrating experiences with dell and alienware. I will probably never buy from here again, to be honest.

I've just come across this same issue. Using the work around I found online I was able to get the keyboard working, but only until the next restart then I had to use the method again.

Work Around Method -

Use on-screen keyboard to log into windows.

Open device manager and locate the Unknown USB device showing trouble.

Uninstall Device

Use power button to put laptop to sleep, then wake up again with power button to log back in.

Keyboard will work until next reboot.

After trying different things to update this driver I finally found a permanent fix. Navigate to Dell support drivers and downloads page. Under the Category filter check off Mouse, Keyboard, & Input Devices. Install the Intel HID Event Filter Driver. after a reboot my keyboard has been functioning properly.

Popping in here to say that this issue is still happening. Great job, Dell - you have permanently destroyed my confidence in your ability to build computers. I use Macs for most everything anyways, my Alienware m15 r6 was a gaming laptop and will now be going to ebay to become someone else's problem. 

My solution was to use the on-screen keyboard to get through PIN screen, then uninstall the unrecgonized USB device in Device Manager, then download a BIOS update and restart.

Thanks to all the other users who submitted workarounds and fixes. Why Dell cannot straighten this out after 2+ years of this issue happening is beyond me. 

Been using the workaround for about 8-9 months now, there was a recent alienware update but that didn't work. Reporting in another R4 user without a working keyboard.