820-3332 dead gpu?

So, I have this 820-3332 machine I bought from eBay because I'm an idiot.

As soon as I got it I could see melted plastic and ripped up screwposts near the gpu.
However the seller seems like a nice guy and said the laptop was like that when he bought it, but it's been working until recently. He also refunded me a good chunk of my money so I got an alright deal overall.

Q8930 was shorted so I replaced it along with U8900 from a donor board. Now the laptop will start and chime, but I get no voltage at L8930/L8960, and therefore no image or backlight. This is because GPUVCORE_EN is low/zero, but U9100 area looks good.

In the past I've seen dead GPUs on these boards but usually it'll at least get VCORE and show an image with artifacts. Should I just give up and bypass the GPU or is something else keeping GPUVCORE_EN low (it's not shorted to ground, I checked)

Any help is hugely appreciated, thanks
 

Gurmon

Member
Best bet is to look for knocked off components.

What's ohm reading of GPU, cant be a dead short?
 
I've got about 25 ohm to ground from GPUVCORE on L8930/L8960, which seems ok I think. I compared the U8900 components with my donor as well as photos online and everything seems to be in its place
 
Yeah, on my cheap-ass oscilloscope I can see all power lines on page 88 come up for a split second then go down.
Whoever had a go at the board before me heatgunned the gpu and longscrewed near Q7880 so I didn't have much hope tbh.
Board seems to work ok with the gpu bypass (of course no backlight control or external video) so I guess it is what it is.
Thanks anyway for your help
 
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