We don’t have all the details yet, but several things are certainly suspicious, or at least worth-asking – things such as why the purge of suspected military officers and judges happened so swiftly, why the military didn’t manage to get their message across effectively, and all that.
Several sources to look at: here, here, and here.
Auto-golpe is a reference to Fujimori’s self-coup as a pretext to disband the parliament and amass excessive presidential power during the 1992 Peruvian constitutional crisis.