They took the beer through an emergency exit, which my son was told made it a felony.
What are the possible penalties?
Without knowing exactly what statute your son is being charged under, it's difficult to know what the penalties are. I am not aware of any "emergency exit" significance in the statutes or the case law, but if there is one the prosecutor will likely state the basis for it in the formal charging documents. From your description it sounds more like third degree theft, which is a gross misdemeanor, not a felony.
One potential penalty I can tell you is for conviction of an alcohol related offense, juveniles over 13 and under 18 will lose their driver's license for one year or until age 17, whichever is longer.
In your son's case, there are likely to be two options. The first option is that he may be offered a diversion. This is kind of like an "intervention" where he may be required to do certain things, such as pay restitution, perform community service, maintain good school attendance, etc. He will have to stay on good behavior for six months. If he shows he can make better choices during that time, diversion results in prosecution being dropped. If he doesn't make it through the diversion, the charges can be refiled. Most of the time, first-time offenders of non-violent felonies are diverted. First-time offenders of misdemeanors or gross misdemeanors are statutorily required to be diverted.
Option two is if diversion is not offered for some reason, your son will have the right to a trial in front of a judge and any sentence will depend upon exactly what he's convicted of. Time in a detention facility is possible, as are fines, probation, alcohol treatment, and other similar restrictions and requirements.
Juveniles are entitled to be represented by an attorney, and counsel is provided at public expense if he cannot afford to hire an attorney. The attorney can and should be a resource for your son. After reviewing the charging documents and the facts of the case, the attorney should be able to give you a good idea of what is customary in your community and what you can expect to happen procedurally.
Lastly, as in nearly all circumstances when a person is accused of a crime, it is prudent for your son to exercise his right to remain silent. If you have any questions about whether he should speak to the police or what he should say, please contact an attorney right away before making any statements.
Criminal Defense Attorney
I agree with my colleague that this sound more like a gross misdemeanor Third Degree Theft/Shoplifting than a felony.
What could potentially make this charge a felony is if your son was previously trespassed from the grocery store and came back and committed the theft of beer. If he was previously trespassed and then came back to steal the beer, he could be charged with Second Degree Burglary. I have written a legal guide on this issue.
Another possible reason for a felony charge would be if your son assaulted someone during the taking of the beer but it does not sound like it from your question.
Otherwise that would have to be VERY expensive beer to rise to felony level theft.