Lenovo G580 - no image after long screw damage.

[PopcornMobo]

Not long ago i bought myself a Lenovo G580 with broken hinges and torn LCD cable. The next day after i bought it i fixed the LCD cable and powered the laptop to receive a nice image. Next step was to TIG weld the broken hinge and fully reassemble the laptop - ready to be used. That's when i did my big mistake and long screwed the mobo while screwing the HDD caddy in. I quickly noticed that i was long screwing the board and only barely just made it under the solder mask, nevertheless the damage was already done and now i can't get any image neither on the display nor an external monitor. I didn't have a schematic or a boardview but i managed to beep out that the via, that i temporarily shorted to ground, connects to the cathode of the diode that separates the RTC battery from the 3V supply.
I tried checking all the rails that i could without any schematics to reference and they were all there as far as i can tell. I thought i could use some help at this point so i came here.
Ps: the solder mask was scraped off to check for any shorts.

[jasko_jacker]

Re: Lenovo G580 - no image after long screw damage.

The only boardview (LG4858L instead of LG4858) I found does not help us.
With a help of a lens try to separate the layers inside the hole using a scalpel and look for another equal board to understand with a tester if the damaged "pad" is connected to a component or to know if it is a known signal.

[PopcornMobo]

Re: Lenovo G580 - no image after long screw damage.

Thanks for the boardview. If i'm correct the via is connected to RTC_AUX_S5. When i measure with the RTC battery removed i get 0.2 Ohms from the via to pin 3 of Q6001, i get the same resistance when i directly short my probes so the via is connected to pin 3 of Q6001 directly. With the RTC battery back in i get 2.898V at the via that got shorted to ground by the long screw. It really doesn't look like much damage is done but i could go and pull the ground plane off the board where the long screw damage is since it's just solid ground there.

[PopcornMobo]

Re: Lenovo G580 - no image after long screw damage.

I removed the copper where the screw damage was but nothing changed.

[PopcornMobo]

Re: Lenovo G580 - no image after long screw damage.

The via connects to RTC_AUX_S5 and it only directly connects to the PCH1J and U2701A, everywhere else it goes through a resistor of at least 20k Ohms. Next thing to check would be the 3D3V_AUX_S5 that got shorted to ground when the screw touched. I'll also go and double check the LCD cable to check for broken wires as well as to replace the electrical tape with some kapton because the electrical tape is a bit too thick. 3D3V_AUX_S5 comes from TPS51123 so i'll have to check if it's still good.
Quick edit: My PCH is getting toasty at power-on so i think it's cactus. Everything else is fine, VCC_CORE is there indicating S0 state. Haven't checked the LCD cable yet.
Yet another edit: I think the repair is no longer economically practical so i'll be leaving this board alone.

[bumper1]

Re: Lenovo G580 - no image after long screw damage.

Mayby this helps

[PopcornMobo]

Re: Lenovo G580 - no image after long screw damage.

Thanks, i already had the schematic, which is why i knew where the RTC_AUX_S5 goes.
I've decided that it's not worth fixing this laptop anymore, i bought it for 50 euro and it came with a 1 terabyte HDD which i can sell for 40 euro, then there's the LCD and the frame and the battery still has 73% health. Parting the laptop out would make me more money than fixing it.

[piernov]

Re: Lenovo G580 - no image after long screw damage.

If you get to an S0 state, the PCH is somewhat working : the power states are managed by the PCH. Also, the RTC circuit should be good too since it's the first thing needed by the PCH. RTCVCC, SRTCRST and RTCRST must be present for the PCH to at least start up.
If you have CPU VCore, parts of the PCH are good, EC is probably good too.
You would need to make sure what the issue is : no POST, no display, no backlight.
For no display/no backlight, it's probably related to the display cable or circuit near display connector since the cable was damaged.
If it's no POST, this is one of the hardest issue to diagnose, but sometimes flashing the BIOS may help. Also check the CPU reset signal, it must be high for the CPU to start processing BIOS' instructions. If it's low, you may have a missing power rail. Sometimes this is caused by a bad PCH.