Remove woodchip that seems to be welded to the walls

You can buy a spikes roller which puts loads of little holes in the paper for the water to get behind it easier

The very handy gadget with spikes on is called a 'Paper Tiger' which is very easy to use to brake the surface of the paint, allowing it to then absorb water. So then soak the walls several time with a large garden water sprayer, far more effective than a steamer. Best o luck, Paul