I can see a lot of positives in your profile. Starting your own company is a great achievement and will set you apart from the competition. Your work experience is also quite valuable and will set you apart from other applicants. If you have decent extracurricular/interest-based volunteering activities, that would give you a very holistic profile.
Coming to your concern about whether 670 is a good enough score. That depends on where you are applying and what are your career goals post MBA.
For example, the median safe score is 720+ to secure admission to the top schools, however that does not mean that applicants with less than that have not been admitted. If your career path and goals align with the ideals of the institution they will give you an admit irrespective of your score. Hence, it is important to identify the school fit and apply accordingly.
If you feel a score of 670 does not do justice to your capabilities, you should attempt the exam once more. Else start working on your motivations for an MBA and career goals essays.
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