LG range - 3 top burners do not function

[as]

LG LRE30453ST range.  3 top burners do not function (LF, RF, Warmer zone), other 2 top burners DO function LR & RR.  The 3 that don't function exhibit the same behavior.  Press on/off, then the two dashes "--" flash, which is waiting for the user to input the temp setting (LO..HI).  Temp setting does not change by pressing the up/down arrow buttons.  The display just has the two dashes flashing and time out after 15secs.
Don't know if it is the Main PCB, Display PCB, Power Transformers??  Any help would be appreciated.

[nolling43]

Sounds like the Touchpad to me (User Interface).

[as]

I was reading through a repair manual for a similar model (LRE30451) and in the manual it mentions replacing the Main PCB first, and if the problem still persists then replacing the touch pad.  I don't want to replace both $$$.  Is there anything I can check or measure(ohm, volts, amps?) that can lead me to buy the RIGHT replacement part?