Hi
I had the same problem with my Hitachi AirCon. I asked the experts here, what I can do to avoid something like that happens again and they told me, there is nothing I can do....
After they fixed it, I reopened the whole thing. On my board there is a small whole, where one can put the finger inside to open the board. This is the only way the Gecko could crawle in. I closed this whole - that's it. See attachement.
The price for my board was about 5500 bath.