A week ago the LCD on my Acer got cracked. I could still power on the netbook and operate it as usual but 1/4 the screen was dead. I got a replacement LCD, took apart the top part of the laptop, and replaced the LCD. Now, when I turn it on, the hard drive and the CPU fan sound like they've started up normally, but after about 3 seconds the laptop turns off (varies from about 2.5 to 3.5 seconds). The screen hasn't displayed anything by this point.
Heat is not the problem. I disassembled the bottom half and unscrewed the CPU heatsink/fan and felt the thermal grease while turning it on; it barely got warm after a few tries. The battery is not the problem; this happens whether on DC or AC power (and the battery's voltage is as expected). I tried replacing LCD with the original but with no effect. I tried removing the LCD altogether (also tried removing HDD and RAM). No such luck.
When replacing the LCD I did cut the plastic tape that was covering the connection between the laptop and the screen (the tape was covering where the connector entered the socket on the LCD). I don't think that should've affected anything though. The only other operations when replacing the screen were unscrewing a few screws and popping off the bevel. Is the only conclusion that my motherboard is fried? I don't see how that could've happened though.