|Did you replace the keyboard or did you take it to a shop?|
You could try disconnecting the internal keyboard and then use a dry cotton cloth to wipe the bottom side of the keyboard. Then reseat the connection and try it again.
I just replaced a dell laptop keyboard. Bought a brand new Dell keyboard for $39 plus $10 UPS shipping.
Dell charges $89 for a new keyboard
Also, try an external keyboard and see if it has the same problem.
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