So in our microwave there is the outer glass, then the metal grid, then a
layer of clear plastic over the grid. .

For nondisclosed reasons, there was a metal object inside and it sparked, a
spark flew to the plastic which melted.. The metal grid is ok.. But there is
small hole
in the inner plastic..

When I microwaved a glass of water some water vapour came through the small
hole and condensed on the outer window..

Is the microwave safe for using?

I think it is but my wives father claimed it is not..

Again, the metal grid is ok..

Anyone know?