1.gloss over

Never try to gloss over your mistake, that would make it worse.

2.within an inch of one's life

They beat Tom within an inch of his life, which brought them into the jail.

summary:

Harry failed to stop Dobby playing a trick, which destroyed the cream pudding and made a mess in the kitchen. Before the Dursleys found, Dobby had vanished. So Harry was blamed for all of this. And he received a message, warning him to be expelled, sent by the Ministry of Magic. Having known Harry cannot use magic outside school, his uncle locked Harry into the bedroom.