Corruption. They bought enough people in key positions. Do we know how many officers of the presidential guard were killed or wounded by the team that kidnapped Maduro? Yesterday I only heard reports of the bombing in the news, but not a word about the fight inside the presidential residence (except of course Trump’s bullshits). Perhaps soon we’ll find out that it wasn’t a fight, at all.

EDIT: btw Trump also said that they knew about the safe room and the team brought equipment to open it. It’s hard to believe that CIA agents infiltrated the residence ala Splinter Cell to find out this details. I’m afraid that Maduro was simply betrayed by his people.