My parents' laptop (Lenovo G780) will not boot.  Here is the explanation I was given.  It was operating on battery power and running the screen saver.  My dad went to the area at my brother's house where they were staying while visiting and plugged the power cable into the laptop and then into the wall.  Dad said that there was no noise.  The laptop just instantly shut down.





Believe me when I say that every troubleshooting tip in the Lenovo forums have been attempted.  Even the "push the power button eleven times and hold it in on the eleventh one" idea.  





The battery gets juice enough to charge and the indicator light is working properly.  There are no beep codes.  When a power on is attempted, it indicates power, but the screen remains blank and the CPU fan never moves.  After six seconds, it shuts off.  No matter what method I have tried, after six seconds it shuts off.





My guess is that there is something on the board that is messed up, but I cannot tell what.





My buddy and I tore the laptop apart and could not find any tell-tale burn marks on the board, but we are not always that lucky anyhow.





I am steering toward buying a replacement motherboard and CPU fan.  Any suggestions that differ?

 

Hook a dvom up to the power supply and make sure it didn't die.

The output is labeled 20v, tests at 20.76 with a Fluke

if you have power then yes id say motherboard next. Process of elimination that way.


ETA: when you say blank do you mean white or black.

How old is it?  Good chance the battery is just TU.  I'd look hard at that before jumping to motherboard problems.

This is a good first step.  I'd try it w/o the battery on just wall power to see what happens.  If you can get access to a different AC adapter it'd be worth trying one just to eliminate that.   I've seen power supplies test good on voltage, but not work and a new PS fixed the issue.

I would also look long and hard at how much money I was getting into when it comes to replacing the MB on a laptop when you're throwing parts at a failure like that.   It might be cheaper in the long run to just replace the whole thing.

edited to add:  I've seen a very similar issue before.  In that case someone plugged in a radically different power supply.  (I think it was a 48v for a Cisco AP into a laptop.)  Are they SURE they plugged in the right AC adapter?

2nd edit:   Another option would be an unlisted option like plugging in a network cable.   I've known people who had digital phone systems in their houses and bad things can happen when you plug a network cable into a RJ45 jack for a phone system thinking it was a network connection.   Did they do ANYTHING other than plug in power?  (If you get the impression I don't believe users, it's because they almost never tell you what happens.  You either have to figure it out on your own, or work it out of them.)

Often, such symptoms are the result of a short-circuit protection mechanism tripping.  Disassemble the laptop, look for obviously failed/shorted components, and reseat all devices and cables (including flat ribbon cables).

I've brought more than one laptop back to life by just reseating EVERYTHING.  

This is worth a try.

 

I am guessing that the motherboard is bad.  I put the whole thing together again (twice to make sure I got all the ribbons in place) and it behaves the same.  





I discussed it with my mother who is ready to move forward with a new one.  No harm, I suppose.  





Thanks to all who attempted to help.  





Also, I did a search for parts for this laptop on Amazon, purely out of curiosity.  My findings were that I could buy all the parts from the same person, but the motherboard was not available for sale.  I'm guessing that this model had a motherboard issue.  Oh, well...

 

It's funny but this issue led to me ordering three laptops, one for my mother to replace this one.  Good prices too.  Too bad the deal isn't still on.