Hi, bought my i30 secondhand a couple of years ago and the dealer explained that the instrument panel had been changed so the car's actual mileage was more than that shown od the display. It had been changed by Hyundai dealer and recorded in the service record book.
It was a bit of a shock when a few weeks ago it started flickering again.
Although out of Hyundai warranty I took the car to my local dealer hoping that, as it seems to be a known problem, there may be something they could do. I shouldn't have waisted my time - no help there !
I gave some thought to the issue and the fact that LCD panels use very little current so oxidised connectors maybe a problem. Then I thought about the Instrument dimmer control and how it works. Unlike days of old when it was just a variable resistor I guess the control supplies a variable voltage to the instrument panel so if there is probably an earth on the control and it goes high resistance because of poor contact the output would flick between controlled and full voltage.
Anyway by removing the fuse panel cover at the end of the dash when the drivers door is open you can get your fingers to the connectors of the dimmer control. With LCD on and flickering I pushed and fiddled with the dimmer control connectors and the LCD stopped flickering and has been fine for the last few weeks ( fingers crossed !! )