Alright, after this nightmare, I finally fixed the lid sensor issue (hall sensor) and probably found out why this is as massive as it's, literally a lot of people online having the issue of black screen after they close their screen on devices with only months of use, sometimes no backlight and as solution people tell you to press the on/off button for 30s, or do a cmos reset, which works, you discharge the system, but once you close your laptop, the issue returns.

First of all the lid sensor is located on the right side of the webcam inside the screen (on lenovo S740), so pretty...

Well I got one last issue, when I close the cover it won't turn on again, the little led just keep flashing normally, I have to disconnect all the power and turn it on again, also when it enters in suspension on windows also won't turn on and when I turn it off, and close the cover and plug the adapter, then open the cover and try to turn it on, also won't. I'm guessing the hall sensor, do you have the schematic or that part, so I can check it? My last option would be some ball under the pch got faulty, but gotta check hall sensor first....

Alright the s740 is working, no touchscreen tho, just as a regular laptop, I got it with a 3v power supply exploded, among other failures, so I'm quite happy tbh (it just gets pretty hot sometimes-->small heatsink), thanks to mon2 for the help

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Alright, no problem, I will assembly the laptop later today (still curing the glue on the hinges), I hope it works, I mean I did quite a few things on this, got it for cheap tho. Some of the failures were the 3v power supply burnt and welded to the pcb (had to grind it), 1.8v rail shorted from 20v, then replaced the pch, did the bios ME, replaced the thundebolt ic, also a drmosfet from the cpu got shorted while testing and in the end this little ic, I just hope this thing turns on tbh, it did recognized my usb tester, so I have some hope. Thanks again, I have some clarity now. I will update if...

Thanks man, this was one hell of a job, I spent hours looking for this ic, at least you found the specific one. In the end I might just leave it like that, no touchscreen....

It's a EL571 LA-H231P Rev: 1.0
Mon2 found the ic NLSX0905MNR2G but still I can't find it anywhere to buy or find a replacement....

Thanks a lot man, now I still can't find this ic anywhere to purchase, this is insane....

I was checking the ic connections and the power comes from the 3v on pin 6, now it makes sense this ic got burnt (3v was one of the first failures), and pin 1 goes into the screen/edp connector, so probably a power supply for that....

Hello I'm currently repairing a lenovo ideapad s740 (intel i9 9th gen + gtx 1650) had got most of the issues solved, but in the end one ic is burnt and gets pretty hot, an AJ7, it's a 16leg qfn 2x3mm ic, I tried to find this everywhere, but couldn't make it, there are some AJ but those are different. Now this ic Is close to the first mosfet (it's not connected tho), in that part of the board there's nothing except for the edp connector and a little fpc that leads to some led signals (cpu, lenovo key and that kind of stuff).
I leave a picture of the ic on both sides, maybe someone knows what...