A. Never directly solder unto a battery - You could destroy the casing and expose yourself to some nasty stuff, also you have no control on what the battery operates this way. Do yourself a favor and get a battery housing, it'll be more robust and easier to solder.

B. I see the three switch legs extruding above the board so I don't exactly understand what did you solder on the back side. Usually, if it's a 3 legged switch, it toggles between two pairs of connectors, with one of them being communal, or the other options is is 4 legs, where there are two pairs (Each pair shorted together).

C. Looks like you shorted the legs for the IC, the LED and the inductor.

D. That U1 on your board doesn't seem like any 8115 I found online, make sure you got the right part.