Suspected lid hardware problem S7 392

I think the the mechanism that detects whether the lid is closed on my S7 392 might be malfunctioning.

• With the lid closed, I can turn on the laptop by hitting the power button on the side (I understand this is not supposed to be possible, correct me if I'm wrong).
• In Windows 8.1, I have the power options set to Sleep when the lid is closed: however, closing the lid doesn't put the computer to sleep. Closing the lid doesn't even seem to turn the display off.
• If I put the computer to Sleep using Fn-W, closing and then opening the lid doesn't wake the computer.
• I Hibernate the computer overnight, with the lid closed. When I check the computer in the morning, the laptop has woken from Hibernate by itself several times overnight for unknown reasons and at seemingly random times and only gone back to hibernation after the idle time out. I've disabled allowing any devices to wake the computer and disallowed scheduled tasks such as Windows Update to wake the computer.

I suspect that the lid is not consistently detecting that it is closed, or maybe there's something loose which is causing the waking by itself.

Is there anything else it might be? What is the process & timeframe to get a repair fo this sort of thing (I am in Melbourne, Australia)?