I was going to reply and draw circles around those two solder connections. That's likely your in and out and as @Gadestroyer74 said if you can put batteries in and a multi meter you can tell which post should be positive and negative. Actually, you don't even need to do that likely...the battery nearest each solder connection is probably the current direction based on which end of the battery is closest. So if the battery near the lower one is negative facing and the other one is positive facing, then you have your answer...that's your current flow. And then you put the red on the positive and the negative is black.The wires were broke off the battery cage but they looked to have been soldered on to the poles (circled) at the top of the cage but I couldn't tell what went where. There is only one wire coming from the camera but inside the sheath looks like 2. If there were 2 wires coming from the camera I would figure + and - on poles just like a typical electrical connection.View attachment 1176167
Good idea and adviceBy the way get two alligator clips and load the batteries in, then clip it on the two solder joints the way you think it goes...if it will power on you got it, it won't swap them and try again. There are only 2 ways with a DC circuit. The wrong way won't hurt the camera like it can on AC.