Sorry about your bad decision. I'm not sure that independent phone repair shops are a good idea, as they keep cranking new, improved models out quickly, and so many people insist on quickly upgrading to the latest, greatest model, to show off how trendy they are. It's pretty stupid, but that's the way people are, so there isn't that big a demand for phone repair services. Besides, for what it costs to get one fixed, you can buy a new one.
I would also avoid trying to do tablet PC repairs. The same reasons that apply to the phones also apply to them.
Is there some related field you could get into? Or how about providing some other service or product in your shop? How about selling accessories and how to manuals (Idiot's and Dummies guides, etc.) for phones, tablets, and computers?