I would doubt there was a warrant. They can always justify it on “reason to believe a felony is in progress”. No officials will be punished, you can bet on that.
Basic detective work is a relic of the past. The informant doesn’t identify themselves. Strike one on credibility. The cops made no apparent effort to gather their own intel on the supposed criminal or the target premises. Strike two. They even reject counter intel on the subject from a relative who appears in person to vouch for him and offers to enter and contact the subject. Strike three.
Did they even try calling the guy on the phone? Wouldn’t that be step one in a potential hostage situation?