PCD8544 not working

Is the display the one you got with your Pico? Does there seem to be any damage on it? is the front loose?

Just to check, does the backlight light up for the first bit of example code on that page:

A5.write(0); // GND
A7.write(1); // VCC

// Setup SPI
var spi = new SPI();
spi.setup({ sck:B1, mosi:B10 });
// Initialise the LCD
var g = require("PCD8544").connect(spi,B13,B14,B­15, function() {
  // When it's initialised, clear it and write some text
  g.clear();
  g.drawString("Hello World!",0,0);
  // send the graphics to the display
  g.flip();
});

Or is it for the second example only?

It looks a lot like the LCD manufacturer sent me a really poor batch of displays (I've had to throw 40 of them away because of dead pixels/etc), so it wouldn't surprise me a great deal if there did turn out to be a problem with yours.

Assuming the display is plugged in exactly the same way, I'm not really sure where to go with testing, short of sending out a new display - unless you know someone that has a similar display you could test with?