Could be anything from a faulty https boot server, to a faulty network connection to a system where the internal drive has failed, defaulting to a boot method you don't have available to you.

You'll need to provide far more information on what's happened to the system and what you're trying to accomplish for anyone to help.

my system Dell Latitude 3420 After open display are blurring(screen off, Screen on) like this only curser are working neither keypad work, I've been very upset. 😞😞

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My watsapp no