Get a stabilizer bar for your extension ladder. It makes them much more stable and all the ones I’ve seen had padded feet on the ends which will also keep you from scratching up the wall.

Assuming this is on its own circuit and you’ve got the space in your panel you could make whatever repairs to the conduit you think are practical and then swap the breaker for an arc fault circuit interruptor (AFCI). That should trip under any failure conditions you are likely to experience but it won’t stop the problem from getting worse. It’s not up to code either but I wouldn’t be too concerned about it under those conditions. That’s also assuming the wire run you can see during your repairs seems to be in decent shape.

There’s really no substitute for digging it up and replacing the whole damaged section of conduit but my suggestion would be a serviceable solution if that is untenable for some reason. It certainly doesn’t come without risks but neither does the situation you’re currently in.

You can try to tap the boards together with a hammer and the pry tool that you used to install the boards. However, that only really works if the boards are properly connected but not fully seated.

It looks like the two in the pic are not connected at all and they’re just sitting next to each other. In that case you’d have to disassemble the floor and make sure to attach them correctly. It’s not terribly time consuming if you don’t have to cut any new pieces.