Your boyfriend should consult with a DUI defense attorney who practices in your area. Depending on the facts in his case as well as the time frame of his plea, it may be possible to withdraw the plea and contest the DUI. Whether that will makes things better or worse is something an attorney can advise during a consultation.
Did your boyfriend request counsel? I would have your boyfriend consult an attorney in the jursidiction where he entered his guilty plea to assess the possibility of withdrawing his guilty plea and the possible benefit and outcomes of doing so.
DUI DUI defense Admissibility of standardized field sobriety tests DUI as a criminal offense Field sobriety test for DUI DUI charges DUI appeal Criminal defense Criminal charges Crimes against society Defenses for criminal charges Criminal court Evidence in criminal cases Admissible evidence in criminal cases Appealing a criminal conviction Evidence Appeals