With println you can debug

The conversion to boolean can work, I think.
Just try:
println(boolean('0' - 48));
println(boolean('1' - 48));
I would have written: boolean(Grid[i].charAt(j) - '0');
to avoid having this 48 magic number, using the char constant makes it clearer.
I would have coded the sizes (70 / 69) in a constant, too.

Now, there is something else suspicious: if (Blocks[i][j] = false) {
Well, it is not suspicious, it is deadly wrong...
That's why I often write to use booleans as booleans, ie. rewrite this test as if (!Blocks[i][j]) {
This would avoid to assign the variable instead of testing it. In other words, you used = instead of ==, and with booleans that's the only case in Java where this error is possible (unlike C/C++ where we have more opportunities to make this error, weee!).

1.      if (Grid[x/16][constrain((y/16)-1,0,70)] > Grid[constrain((x/16)-1,0,70)][y/16] && Grid[x/16][constrain((y/16)-1,0,70)] > Grid[constrain((x/16)+1,0,70)][y/16] && Grid[x/16][constrain((y/16)-1,0,70)] > Grid[x/16][constrain((y/16)+1,0,70)]) {
          x += 16;
        }