Estimuló comes from the verb estimular, meaning 'to stimulate' or 'to encourage'. While it can refer to physical stimulation, in this context, it's about emotional or mental impact.
In the song, the narrator says, "Cuando me dijeron que no me estimuló" (When they told me, it didn't stimulate me). This suggests that the news of Martín's death didn't provoke a strong emotional reaction or a sense of urgency in the narrator at first, making it an interesting and somewhat detached way to describe a significant event.
Pavel Núñez's "La Muerte de Martin" is a really interesting song about a delayed reaction to loss. The singer finds out that Martin died, but he didn't know it at the time, saying "se murió martín yo no lo sabía" [Martin died, I didn't know it]. He only found out about it "hago 15 d" [15 days ago].
What's striking is how he describes his initial reaction: "cuando me dijeron que no me estimuló" [when they told me, it didn't stimulate me]. It wasn't until later that the sadness hit him, making him wonder, "ay por dios cara más que está en la mente" [oh my God, what else is on my mind?]. He feels a deep regret, repeating "y qué pena me dio" [and what a shame it gave me]. It seems Martin was a significant person, as the lyrics mention "la carretera le prendieron papá porque no había verdad" [the road lit up for him, dad, because there was no truth], suggesting a powerful impact and perhaps a sense of injustice or a sudden, unexpected end.