However, if the company hasn't made much money and doesn't have any customers, then there is virtually no brand/identity and the IP is nearly worthless. Your goal now should be to avoid being liable for the company's debt and documenting a clean break while leaving on good terms. This will allow your cofounder(s) to continue on if they wish to do so while leaving you in the clear to pursue other interests.
If I were you I'd sign a document giving all IP and rights/equity you may have had back to the company and walk away. Hire a lawyer first before doing so to verify that you are in the clear.
I'd write off the time you put into the startup and consider the effort you put in as an educational investment in yourself. And congrats!, you just walked away from your first failed startup, I hope you learn from it and get back on the horse asap.