My son's Sony VAIO VGN-NW240F/T failed and thankfully he let me have it. Turned out to be a bad HDD. This laptop was from 2009 so for a test run I pulled the HDD out and ran a Linux off USB for testing. Convinced the HDD (which to annoy me passed all HDD diagnostics) the HDD was replaced and the factory restore performed. Working OK now but the battery is tired at 30% wear (thanks Batterybar.)

If the no HDD test doesn't work you may as well keep disassembling further. The time I found a staple inside still is a classic.