On my Vostro, the buttons have to be slid OUTWARDS, not inwards, to release the battery.

The connectors (tags) are welded to the battery, not soldered. Do not try to use a soldering iron to detach the tags from the battery - it won't work, and the heat could cause the battery to burst and cause injury.

Generally the new battery comes with new tags attached, so I think best practice is to unsolder the old tags from the circuit board.

When obtaining a replacement hard drive, be aware that many 2.5" laptop drives, particularly older ones, are too thick (9.5mm) to fit in the X220 drive bay. You need one with a drive height (thickness) of 7mm.

When obtaining a replacement hard drive, be aware that many 2.5" laptop drives, particularly older ones, are too thick (9.5mm) to fit in the X220 drive bay. You need one with a drive height (thickness) of 7mm.

At about this stage, as I was working on the fourth side, the layer of black paint on the inside of the glass started to separate from the glass, near the edge. I may have overheated the phone (I used a heat gun). Most of the paint layer ended up left behind, attached to the body of the phone, as the glass came away - along with the lens covers of the camera and flash. I removed and discarded as much of the paint as I could using tweezers, a spudger, and cautious heating with the heat gun. I hope the back glass will work OK without it; a clear back cover will be a distinctive design feature! If not I’ll have to get a new one. (Note, some battery repair kits from other suppliers such as Amazon include a replacement back glass, which would help with this issue).