The action key is not working even after enabling it in BIOS. Also it doesn't work by pressing 'Fn' key. Also sometimes the keys are not working while trying to sign in at the time of turning on the system.
I think it would be a good idea to take apart the keyboard, or some of it, to determine if the keys are obstructed somehow. Some information on the supported method of cleaning the keyboard is mentioned in this document: Cleaning your Notebook PC
If this does not resolve the issue, I would reinstall Windows on the computer. The issue at this point would be software related, to some unknown extent. A recovery will address any software issue. First, make sure you backup everything you need to. Here is some information on how to do this: Backing Up Your Files
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