Laptop was working just fine for 2 years, in one day Windows10 crash due to some unexpected errors - blue screen.

at the end I had a black screen and nothing was really works, I cant even access bios, trying everything I was able to find over inet. (originally I had 8Gbx2). 

after trying everything possible, I was able to isolate the issue and start the machine but only using one RAM slot, if I switch the memory slot, or insert in both I receive a black screen and mainboard not starting, same as on this ytube video link

for now I have 4 memory chips (8Gbx2 and 16Gbx2) but laptop starts with any of the chips but only on one Upper slot. Any solution? as looks like this is not just me,

lease advise