A single light bulb illuminated the other contents of the bare, musty room: two plastic chairs piled with clothes, canned fruit and vegetables, and a single gas burner.

Mr. Marrero, a community elder known to his neighbors as Don Ramón, draped a towel over his bare back to fend off the mosquitoes. Earlier, he had walked to the post office to charge his cellphone and mobile battery pack.

The only electricity he had seen since the storm came from an extension cord connected to a shared generator donated by Luis Fonsi, the Puerto Rican pop singer who filmed the video for the hit song “Despacito” in La Perla.

Mr. Marrero was hesitant to plug in the light bulb or his electric fan — only one could be used at a time — because he was afraid to overheat the machine or take energy from his neighbors.

Residents of the barrio say they were left to clear garbage and other debris on their own after the storm because municipal workers had failed to show up. Like Mr. Marrero, they were using fallen branches to fuel bonfires for cooking.

Lorel Cubano, the director of a local nonprofit, said most of the aid the neighborhood had received was from private citizens and celebrities like Mr. Fonsi. “The government hasn’t arrived here,” she said.