Hi Sheau,
This could be due to the power failure on the Laptop during the installation of Windows 8.1 update on the computer. It seems that you are getting a "***Blue Screen Error***” on the computer. These type errors usually occurs when a serious problem causes Windows 8 to shut down or restart unexpectedly. There are multiple reasons why this type of errors occurs on the computer. In this case, the issue could be due to the damaged or corrupted System Files on the computer.
The PAGE_FAULT_IN_NONPAGED_AREA bug check has a value of 0x00000050. This indicates that invalid system memory has been referenced. I would suggest you to see the following links:
Bug Check 0x50: PAGE_FAULT_IN_NONPAGED_AREA
http://msdn.microsoft.com/en-ca/library/windows/hardware/ff559023%28v=vs.85%29.aspx
http://msdn.microsoft.com/en-us/library/ms854882.aspx
Note: While performing chkdsk on the hard drive if any bad sectors are found on the hard drive when chkdsk tries to repair that sector if any data available on that might be lost.
Note: Antivirus software can help protect your computer against viruses and other security threats. In most cases, you shouldn't disable or uninstall your antivirus software. If you have to temporarily disable or uninstall it to install other software, you should re-enable it as soon as you're done. If you're connected to the Internet or a network while your antivirus software is disabled or uninstalled, your computer is vulnerable to attacks.
Also Please check the private message and respond to the private message accordingly.
Hope this helps. Let us know if you have any other issues with Windows in future.