Then, you can analyze the industries like :
1. How the competition with Rivalries? Is it vigorous?
2. Any close substitute in the market?
3. Is it easy for new entrant to enter the market? - If it is easy for new entrant to enter a profitable market, profitability to decline.
4. Supplier Power - How easy it is for suppliers to drive prices up.?
5. Buyer Power - How easy it is for buyers to drive prices down?
You will then able to cut your list down to 1-2 industries. I would suggest you can then work in the industry some time to understand the operating model and supply chain. Also, it is a good opportunity to safe the monies for the initial investment of the startup.
Hope this helps! Good Luck!