I just want to add that I am another grateful (italian) reader of this forum that happened to stumble on it while searching info about my Samsung NZ84j9770EK induction hob (european model), suddenly not detecting cookware on the left burners, after almost three and half years of zero issues.
After reading al of your posts about the similarly designed (this was my guess) NE58H9970WS, I decide to disassemble my unit to see if the overall layout was consistent to the one you showed, thus leading to the same problem and solution.
As you may guess, the answer is affermative, and I think this clearly shows a design issue with all this serie of (otherwise excellent) induction units.
Possibly, the reason to the soldering fail always on the left side of the inductors could be somewhat due to the PCB layout, that is not simmetrical and could not allow heat dissipation on that spot, which I believe is not reached by the air flow of the big fan nearby. While I do not think this is a case of programmed obsoloscence, this is just my opinion.
I have been lucky enough to find the correct disassembling sequence without any service manual, which I provide below for anyone could have the same problem on this particular unit:
remove the 12 perimeter screws (Phillips) which join the glass surface to the electronics chassis, lift the glass and move it in a secure place;
remove the four connectors from the control and display board you can see in the center-bottom of the unit and move it elsewhere;
remove four couples of red/black thick power cables from each inductor, along with the associated tiny connector close to it;
remove the three tiny connectors providing power to the inductors LEDs (virtual flames), for this unit two LEDs are on the circular "burners" and one is located on the bottom of the "flexi/combo" left burners (the ones not working anymore)
remove 19 Phillips screws (16 perimetral and three more in the central area) plus two bigger screws on arc-shaped slots (upper right quarter of the unit);
lift the induction assembly and move it elsewhere;
access the central board (the one with six the toroidal inductors) by unscrewing 5 Phillips screws (four corners and one in the middl) and by detaching two high current connectors (they are though to extract) and a couple of smaller connectors;
- there you go, you do not need to detach the power cables to the board, just turn it upside down and re-solder the pin.
Just to leave a proof of how similar the defective soldering on my unit looks, compared to the original unit posted in this forum, here is the pic, and I have to say a big THANK YOU to user443854 who struggled to find the problem and finally fix it, posting his findings and helping a bunch of us. Thanks sir, great job !