Burglary is an 'either way' offence, which means that the magistrates can deal with it or it can be referred up to the Crown court. If the magistrates have 'declined jurisdiction', and referred the case to the Crown court, it indicates that the magistrates believe that their sentencing powers may be insufficient. (i.e. the magistrates are of the opinion that a custodial sentence exceeding 6 months might be appropriate).
However, Crown court judges frequently disagree with magistrates, and impose non-custodial sentences on offenders who appear before them on an 'either way' charge. (Additionally, the judge will have access to a pre-sentencing report, which the magistrates won't have had at the time of their decision to decline jurisdiction).
Burglary is a serious offence and (when the burglary takes place on domestic premises) the maximum penalty is 14 years imprisonment plus an unlimited fine. So there can be no guarantee that your brother won't be 'sent down'. However, the courts always try to keep people out of prison whenever possible. Your brother's previous good conduct, together with his cooperation with the police, means that the most likely outcome will be a supervision order (= 'probation'), coupled with an order to carry out, say, 200 hours unpaid work.
Chris