Pixels in the LCD matrix of the monitor Are not dead when they stay at a fixed colour when using the monitor.
They are stuck pixels where the colour of them does not change between the red,blue, and green used to make all the possible colour combinations the display can produce.
The pixels if stuck always become more prominent when a large area of colour is produced.
For example with black the stuck pixel can often be red in colour.
It is down to the single pixel it`s self where the liquid crystal and connects of the pixel are not formed properly.
Often there is no fix you just have to live with it.
Or you can try with a soft cloth while the monitor is on where the pixel is stuck pressing on it with a light pressure from your finger to try and activate the pixel in the matrix.
Monitors have a warranty on them where at least four pixels of the display can be stuck, or half functional any more than four stuck pixels of the lcd display and the monitor can be replaced under warranty for free as defective.
It will state this in the warranty agreement for the monitor you purchased.