50 Cent's ridiculous 52-room Connecticut mansion was broken into this morning -- according to law enforcement, TWO men were arrested ... one of whom cops found drinking wine inside a closet.

Law enforcement sources tell TMZ, they received a call around 6AM from security guards at the mansion -- once owned by Mike Tyson -- about a suspicious car in the driveway.

Cops showed up and discovered two men in the residence ... but the second was a little harder to find -- because Alexander Hernandez was hiding away in a closet, pounding a bottle of wine he allegedly pilfered from 50's place.

According to cops, the two suspects entered through an unlocked door -- and were in possession of marijuana when police arrived to the home.

Both men were arrested and held on $50,000 bond.