I had a single bad module, as tagged in the photo below:

No two ways about it, I’m going to have to open everything up if I’m going to get the module out. The modules are pretty packed in there, I guess they’re compressed slightly so they don’t expand while charging/discharging. The white piece of plastic at the end is roughly the size of a module, and keeps everything snug. There are two screws in the two black bars on top that span the entire pack, two screws in two almost identical bars on the underside of the pack, as well as two bolts sticking up through the frame that keep the bottom of the plastic end cap in place – only one of which had a nut in my battery pack.

First things first, there’s a temperature sensor underneath the modules. It’s just a couple relatively small gauge wires, but nothing works if the temperature sensor is damaged. It’s held on with two little black plastic clips that pop right off. It’s hard to see in the picture, but hopefully it gives you an idea (it’s the little white wire on the right):

Jumping ahead to make it more clear, you can see how it attaches here:

It’s fastened in two places:

Jumping back, after that it’s pretty straightforward. Undoing the 4 screws through the top and bottom bars put a lot of pressure on the two upright bolts – I was a little concerned they would break, but it seemed to hold together without too much problem. The plastic part comes off relatively easily.

What isn’t quite as easy is the surprise that is waiting for you after that. The modules don’t lift right out.

Each module is fastened on one end with a screw through the bottom. With everything being reasonably squished in, it seemed like it was going to be extremely difficult to get a module out of the center of the pack – I would have to keep the modules on both sides of the dead one compressed. Instead of fiddling with it and stressing out, I decided I’d take everything out. Before doing this, I numbered each of them, so I didn’t mix anything up. I set the battery pack on a small side table and hung one side off at a time. Slow and steady, and the pack is apart.

Just like that, the bad module is gone!