Randomly turns on, but mainly not.

Its 820-3115-B model.

I had sometime now upgraded to 16gb ram, ssd and it was operating as clamshell mode 90%. Battery replaced but not that good quality and so did the charger, but everything was going well for quite some time. Maybe this new charger is about a month now.

So as I was using it, it stopped suddenly. Black screen. Pressed power button, nothing. So I read and watch some videos and took the m/b out, nothing too extreme or obvious, cleaned with isopropyl alchohol, applied a new thermal paste and away it went. Installed 2 apps to check temperature and everything seemed ok. Until I put it at sleep mode and after it never woke up again. I cleaned everything again, installed one ram module, left keyboard, battery, dvd out nothing. The fan is working but nothing. Then I clean again very well and it starts, then I shut down, try to power again, nothing. The m/b at a specific area gets hot and the fan always spins, sometimes quite a lot. So I have not solved the puzzle.

I'm not experienced locating short's, but I have a multimeter and can follow instructions. No voltage supplier though.

I'm watching some videos, but I dont seem to find my issue how to address.

I would like to find the issue and have this machine keep going.

Any help appreciated !

hot area in yellow - on the other side its the chip next to the cpu

that cap in green does not beep

i took a picture of the other side and I wanted to say that to me cap c7717 seems to be missing

I downloaded 820-3115b board file and a program to view it, so here it went.

the area that gets hot is the U3990 aka SLJ8C

also another question is that on the board file an item R3990 is not on the board, but cross checking with m/b that are on sale its not there either