Remove the battery box from MIP. Remove the batteries from the battery box. Unscrew the two screws visible in the picture above to separate the back plate from the battery box.
Now you should have this:
You need to remove the battery terminals. They slide out without too mich effort. Hang on to them - you'll need some of them later. This is what your battery box should look like:
To make room for the LiPos, you need to cut away the interior parts of the plastic. You can use a dremmel, but a scalpel does a good job of getting into the tight corners. Scalpels are super sharp and easy to snap, so be careful.
Take a look at the picture below to see the end result. It's not important that the middle part of the battery box comes out in one piece. It's the outer part that we want.
Onto the batteries. The battery leads on the LiPos weren't long enough, so need to be extended to reach the protection circuit.
... more soon.