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Need some help to diagnose a laptop motherboard (powers on, no boot)

Joined
Mar 15, 2017
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First of all - the two most important things:
1. Yes, I know that this is stuff people usually charge money for. As this old thing is probably worth less than what someone would charge in order to diagnose/repair it, this exactly is why I'm trying to fix it as a favor. Anyone taking their time to guide me is highly appreciated.
2. Yes, the easiest thing would be to give up and throw it in the bin, but I would want to give it a last chance of life before that.

So, this is what I'm working with - it's an old Dell Latitude D620, a Core 2 era laptop.

What is does: It powers on, the power indicator lights up, but there's no image on the display. The HDD can be heard clicking several times, then it stops. The fan doesn't spin, don't really remember if it did before I disassembled it. The battery can be charged and the low battery indicator is working.

What I've tried so far:
- Initially tested it on battery power, then plugged in the power adapter - no change
- Connected an external display via VGA, tried to cycle through the display options via keyboard shortcuts - no change
- Disconnected an external USB WiFi adapter - no change
- Took it apart and disconnected the HDD and optical disc drive - no change
- Switched around the two RAM sticks, tested them one by one - no change
- Tried it with no RAM - it knows it doesn't have RAM installed, the Num lock indicator lights up and the two adjacent ones blink for a while, then in powers off by itself
- Put RAM back in, tested the battery, it was at 2.7V so I swapped it for a fresh one - no change
- Disconnected the internal WiFi and modem boards - no change
- Removed and visually inspected the board for any signs of corrosion or other damage - seems fine

I'm fairly certain by now that something is wrong with the motherboard, but I don't know exactly what. I have a multimeter at my disposal, can use it to measure voltage, impedance, etc. if guided to certain points. Here's two pictures for visual aid (I can post more detailed areas if needed):

2023-05-06-6126.jpg

2023-05-06-6127.jpg
 
First thing you do, is you hook up to BIOS with the means you can, JIG or flasher read the bios backup and dump an new one.

And only then you are starting component repairs. Otherwise you are wasting time. This thing prolly costs around 20-30€ on fleabay.
 
First thing you do, is you hook up to BIOS with the means you can, JIG or flasher read the bios backup and dump an new one.

And only then you are starting component repairs. Otherwise you are wasting time. This thing prolly costs around 20-30€ on fleabay.
Don't have one of those at the moment, maybe have to borrow one. Forgot to mention that I also thought about the BIOS, but so far couldn't locate the chip.
 
On the A side of the board, it looks like there is surface damage around the SATA connector extending to H14.
If that's confirmed not surface damage/discoloration, to find the BIOS I would start by google chip codes starting around JCOIN, going with the 8 pin chips first, then up to higher pin-count chips. If your BIOS is something like that quad flat pack wedged between the intel northbridge and the WLAN Mini PCIe slot then god help you.
 
Does it have Geforce graphics? If yes, time to bake probably. They were pretty notorious for having bad BGA solder joints.
 
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