If the system is under warranty, hopefully you kept an image of the Windows with which it shipped, because you'll need to reinstall that before you contact Dell support -- they will not support the system with Linux running (no LInux support is offered for this model).

If it's a brand-new system (less than 30 days from shipment) and you purchased it direct from Dell, you can also return the system for a refund or for exchange.

Restore to Windows may help with testing the keyboard for issue.  However, for faster testing if the issue is hardware related, connecting an external USB keyboard.  If the same issue is happened on the external board, it is not hardware.  Check and reset your Linux settings might fix the problem.

@ejn63​ 

I have tried to send it back in US (to Amazone) but it took time more and my Aunt bring it back. 

I have reinstall windows I'm still facing the same issue, which means the problem is hardware but just does not make sens that a new computer have hardware issue, knowing that it's an expensive computer.

@Chino de Oro​ 

I have restore windows, I'm getting the same issue. With an external keyboard it works fine.

I have the same issue, just started last weekend. My Enter, Backslash, and Home keys all stopped registering any input. I've tried multiple solutions and nothing has worked so far. I mapped F2 to Enter as a workaround in the meantime.

Just got a new old stock sent from Amazon that arrived today. Imagine my surprise when I unboxed it and powered it up just to find out the enter key and mute key is not responding. So now its either pay extra money to get world wide support or send it back.