Solved! ASUS ROG751J won't power on

[geo5690]

Story is a couple weeks ago my asus rog751jy laptop fan started making noise. was pretty bad, so i ordered a replacement. got it in yesterday, replaced it with no issue and everything seemed to be in order. nice and quiet. laptop works for about an hour then shuts off without warning. since then, no signs of life. no lights, nothing except some kind of high pitched whirring noise coming from somewhere around the ac plug. i've tried doing a hard reset by removing the battery pack+ac adapter and holding the power button for a minute, with all components+the hard drive removed with no response.

as near as i can tell the noise appears to be coming from this component https://user-images.githubusercontent.com/68093058/88054978-c407fe80-cb4d-11ea-9f2a-b85352bc1ef8.jpg which is the chip right above the tape on the right side in this pic https://i.ebayimg.com/images/g/5GYAAOSw8cFcQZmM/s-l400.jpg either that or somewhere underneath. i haven't tried removing the motherboard, don't really know what i could try.

i have no idea what could have happened. i keep hoping it starts to magically work again because it seems like it just magically stopped. the procedure went perfectly and i'm sure the part was correct. any ideas? in the worst case, should i try a motherboard replacement? or maybe a battery issue? thanks in advance

 

[geo5690]

especially upsetting because i thought i was in the clear, everything was working, fan replacement seemed to be successful, then out of nowhere, suddenly nothing!

my first most hopeful guess is it's just the battery that conked out when charged with the task of spinning a new fan alongside all the other stuff i've got plugged into it, including an lcd and crt monitor hard drives, etc. could that be right and also explain the noise?

 

[COLGeek]

Shutdowns, as described, are often heat and/or power related.

What specific fan did you replace? Did you remove any heatsinks when installing the new fan? If so, did you replace the thermal compound/pads as part of the process?

 

[geo5690]

i replaced the left fan, the cpu fan. didn't need to touch the heatsinks to access them thankfully, just pull the top face with the keyboard off and they're right there pretty much. there's a few connections going to the keyboard which i was careful to avoid tearing in the process, and made sure to reconnect everything as well

 

[COLGeek]

When you was working inside the laptop, was the battery removed?

 

[geo5690]

the battery was in, i just unplugged the ac adapter. after i put everything back together it worked for about an hour then abruptly powered off.

however i found another problem which is i replaced it with the wrong part. the old fan was 12v, i replaced it with a 5v fan. I knew to be careful about this sort of issue, but i guess the mistake happened when i saw a different looking fan but for a laptop model that looked exactly like mine, so then i found this one which looked right and assumed it was the correct part.

unfortunately, now i've tried replacing with the old fan and still i get nothing but a high pitched noise

 

[COLGeek]

You likely damaged the motherboard and it will need to be replaced. Sorry.

Always remove the battery, for future work.

 

[geo5690]

i see, thanks for the help. what's your best guess what exactly happened? since i was also thinking of a battery issue, maybe i want to try replacing that first?

 

[COLGeek]

The improper fan shorted the motherboard would be my guess.