If someone blows under 0.8, can they still be charged?

My cousin was arrested a few nights ago for a DUI. The thing is she hadn't drunk in hours and only had like one mixed drink. She was pulled over for no reason. She passed all the field test and blew a 0.7. She had a friend with her who blew like a 0.2 and told the officer that her friend could drive home and he was like yes, she could've, but didn't let her and arrested her anyways. At the station after she waited, she did the breathalyzer again and she kept asking them what her score was. They said they didn't know. How can they even say that? They told her she would be out by 7am the next day. She was arrested around 2am but she didn't get out till 3:45pm so they kept her there 12 hours because they lost her file. She said all the officers we're super nice and we're confused why she was brought in because she looked not drunk clearly. There was no bail. They just let her leave. I'm sure there's things she could've done or not but she was literally crying the entire time and never experienced anything like this so didn't know what to do. She's an excellent student, never done anything bad wants to get into Medical school and is freaking out that this will ruin her record. Is there a chance that she could have it dismissed? The only problem is she's 19. What are the chances since she's under 21?