I had fried fish at a restaurant and it wasn’t cooked all the way. I brought it home and wondered if it was okay to finish cooking the next day or will it make me sick?
Throw it away, seriously. Foodborne illness risk increases with the type of food, the conditions in which it was cooked and how long it was at room temperature. Given that it was never cooked right in the first place and it probably stood out awhile you really should play it safe on this one, it's not worth getting very sick to save a bit of food, especially since it won't have good taste or texture now anyway.