Never opened up a VE head unit but some vehicle manufacturers used
elastomeric connectors to bridge the space and electrically connect the circuit board to the LCD. Such elastomers can deteriorate (loose their springiness) over time or in some instances finger oils can make its way to the contacts themselves upsetting conductivity. Either issue can result in sections of the LCD being hard to see. Sometimes pressing the display improves the situation for a short time but it quickly fades which is a bit of a giveaway that the elastomer is the problem.
Unfortunately I don’t know if Holden head units use such zebra connectors or if indeed this may be the cause. But if you will replace the head unit in any case, it could be worth dismantling the unit and having a look at how the LCD is connected to the logic board.
If Holden did use such elastomeric connectors, should be easy to fix in theory as replacement zebra connectors used to be cheap and easy to source but not sure of the current state of play in our disposable society.