He needs to call the court, give his name and the case number ***** he knows it so that the clerk can look at the computer and find out what happened on May 10th. That's a very recent date and there's been a weekend intervening. So it's likely that the website wasn't up to date and a warrant did issue. If the warrant didn't, then unless the case was thrown out, a new date would have been ordered, and he needs to know what that is.
Most typically, a warrant would have been issued, and if you/your son finds that to be the case but comes back to court immediately, with only a few days since the warrant and a voluntary return to court, most judges would accept any reasonable excuse for his absence on the 10th and keep him at liberty. The longer he waits, however, the greater the chances of being incarcerated and held at least for a couple of days until the prosecutor could order his case file. In that case, for best results when he comes to court to return himself on the warrant, you would want him to have a lawyer with him.
If there is no warrant, then he was fortunate enough to dodge a bullet this time. You need to encourage him to come to court on the new date.
Your son is at liberty, which typically means that he can resolve his present cases in some way where he could remain so. By playing fast and loose with his court dates, however, he can wind up facing jail time that he would typically be able to avoid.