Hey
mbahopeful13,
Sorry to hear the GMAT is a frustration. Thanks for posting here and asking for advice.
Candidates are admitted regularly to the schools you listed with a 690. Those candidates, however, have to overcome that sub-average score with some shimmer and shine in other areas of their application - their undergraduate prestige, prestige of their employers, community involvement, and superb application/essay/interview execution. Some also get a boost from their demographics.
In your case, you certainly seem to have the employment prestige going for you - maybe. You mention you have worked at 5 different start-ups in 6.5 years. At first glance, that looks awfully suspicious. If you can construct a rationale narrative that communicates how you added value to each in a short period of time, you should be okay. But that is a glaring red flag without further explanation.
Your community involvement is certainly there, assuming you have made a noticeable difference in your various activities. Undergraduate prestige probably does not jump out at the AdComs either based on your post.
Candidly, with a 690, HBS is going to be a big stretch for you. Tuck and Sloan will be difficult, but not impossible. If you choose to stick with your GMAT, a perfectly-executed application could score you an admit.
We are Tuck graduates at Lionheart Admissions, and we have helped clients with similar obstacles get admitted to the top programs. Please reach out if you'd like to chat further about your candidacy!