Dell Inspiron 3542 Keyboard error

Hey all !

I have a Dell Inspiron 3542. Trouble is, certain keys of the keyboard either do not work at all or, they act like they are pressed. 

The keyboard is in good condition - No damage to the keys at all. I've tried uninstalling and updating the drivers, but the problem persists.

I performed a system reset, reinstalled the OS and the problem was still there, but this time, it turned out to be a different set of keys.

I ended up giving the laptop to an authorised service centre where, they changed the entire keyboard and gave it back. It worked out fine till last month.

Then, I had to reset the system again and ... The problem was back. This time, the start key, the left arrow key and the Numerical pad does not work. Plus, the up arrow key acts like its being pressed continuously.

Need help for this issue.