Plant found by dumpster in a paper bag

Awhile ago my brother found this plant by the dumpster in a paper bag and brought it in. He planned to pot it, but left it for awhile and the soil/roots got completely bone dry but it was still alive. Finally potted it for him recently and looked it up, came to the conclusion it was Dracaena corn plant. I was advised to cut the top of the one stem that was very tall, thin, and weak which caused it to turn black?? So now I’m not sure it’s a Dracaena anymore as it doesn’t quite look right with how it’s growing / dying on each stem