Thanks for your reply. I've done some troubleshooting myself after being told by the dell support in twitter to open the laptop and check if the RAM were connected properly. After many tests, I realised that one of the 8 gb memories was dead. I am now with the other 8 gb only, but luckily I am writing this on it. I've called dell technical support and they will send a technician with the memory to my direction. I'm relieved that the warranty covers Argentina, 'cause in this country everything tech related leaves much to be desired. Hopefully, I'll be getting my replacement next week.
I'm still confused about what could've happened with the memory and it's sudden death.