Why Does My Relay Fail?

Hi I am more of a programming guy and new with hardware so please take it easy on me. I am helping my son to build a customize car horn for his toy car which operates on 24V with BLDC motors. I removed the outer body and traced the wires to check how the in-built horn works. It was powered directly from one of the 12V battery through a switch (horn switch) which when pressed turned on the horn. So from this, I concluded that horn operates on 12V, so I replaced the switch with a 5V relay that is triggered by Arduino. The NO and C of the relay are used to complete the connection of horn with 12V battery. I have the tone function on Arduino which switches the relay to output a music. Everything working fine but relay gets very hot and then stops working after like 10-12 times usage. I have changed the relay a couple of times by failure appears again. To find the problem I opened the relay (broke the outer blue casing) and found coils were good but the contact was burnt (in both the failed relays). Sorry I cant take pictures but the i took a picture from internet which looks exactly similar, the burnt area is circled blue. Everything I know about relay including this image comes from this relay article https://circuitdigest.com/article/relay-working-types-operation-applications I have tried the following 1. suspected that current is the problem so measured the current using multimeter found it to be 550mA well within limits 2. Thought I am switching relay very fast so slowed down the tone but still not help So what is causing the failure? is there a special type of relay that I should use?

How fast are you trying to switch this relay? What is the make/model of the relay?