If you can, try to keep the switch pressed with something, like a zip tie or something.
Then, if you have a battery holder , 2x AA or 2x AAA , connect the negative to the spring and positive to the brass case of the diode holder.
While doing so, try alligning the crystal that is partially glued, when you find a sweet spot, just jeave it there for the glue to dry out, but be careful, as H_Mike said, instant glue leaves nasty frost on every optics, so try to apply it on outside of the holders, if you can.
However, as much as I am a DIY person, I must say that it's too much of the trouble, and you will never get the previous power back.
It is all up to you, but I'd simply save for a decent laser from O-like or Rayfoss or similar.