there is a circulation issue as the heat isnt escaping the boiler
More likely the boiler has just stunned itself by firing up at all.
This is where, if it had the ability to make a phone call it would be calling Hull shouting "look everyone - you've made one that can work!"
Whereupon it would no doubt promptly die in a puff of plastic based smoke and dribble sludge and Ali silicate out of its a7se all over the worktop.
Ideal - ****uation normal