Great guide. Just successfully completed my battery replacement in just under 2 hours (going slowly and carefully). Managed not to break anything. A few thoughts:

1. As per previous comments, skip from step 4 to step 34. Completely disassembling your MacBook is too extreme and risky if all you want to do is replace the battery.

2. I removed the old battery by levering the cells up using a large flat head screwdriver. It worked for me, but I'm not sure how safe this is: some of the cells bent as I was doing it and I was a bit worried about causing a puncture, short circuit and/or battery fire.

3. I don't know why everyone is so obsessed with removing all traces of the old adhesive using solvents. Most of the adhesive came off with the battery, and I removed most of what remained using a spudger and my fingers. I didn't use any solvents.

4. Before inserting the new battery, take a moment to adjust the degree of click of the trackpad using the screw in the middle of it, underneath the battery.

The photographs in this guide show two slightly different MacBook Pro 15" Retina machines being disassembled, probably because the guide has multiple authors, and there is a subtle but very important difference between them. Look at the photo in Step 55. This shows the old battery being lifted out of the machine, it has six cells, and the battery connector is located in the centre of the top edge of the battery between cells 3 and 4. Now look at the photo in Step 3. This shows a battery connector which is offset by about 3cm and is above cell 4, not between cells 3 and 4. I believe the offset battery connector is from a mid 2012-early 2013 MacBook and the central battery connector is from a late 2013-mid 2014 MacBook. This is important because if you have the wrong battery, it won't work because the connector won't reach the socket. I found this out to my cost when I bought a battery which the seller told me was the right one, it turned out to be the wrong one, and then I couldn't return it.

I found a combination of iOpener, suction cup and razor blade, all applied at the same time, worked for me and I didn't need to use a hairdryer.

The adhesive comes sandwiched between two sheets of blue release liner, one slightly larger than the other. When you peel them apart, the adhesive is meant to stick to the small sheet, which you then apply to your iPhone. In my case, when I peeled the two sheets apart, the adhesive stuck to the large sheet, making it impossible to apply. I don't think it was anything I did wrong - probably just a fault in the manufacturing process. I will try reassembling it without the adhesive, or possibly using a liquid adhesive like B-7000.

I found using the blunt end of a spudger to roll the adhesive strip off worked better than trying to get hold of it with tweezers.

I couldn't disconnect the battery connector - I applied some force, nothing happened and I was afraid of applying too much force - so I just left it connected and I was very careful not to short out any terminals with metal tools. I completed the repair without any other issues and the iPad now seems to be working fine.