Macbook air refirb

Windows
Was 8.0
8.1 one upon a time had a video display driver issue.
I tried to install win 8.1.  First as an update but I could not get that tor work.  Once upon a time I'd had problems with 8.1 and a driver update issue and I must have found some why to stop it updating.
Tried a clean install (lost everything).  prior to this, i used a keyfinder program to locate the keys.
I downloaded from microsoft 8.1 and created a bootable USB.  Followed instructions from the mac side / boot camp to install but the key was not recognosed.

Decided to install WIN10


Windows 10
Harvey Norman - USB stick - $178
Microsoft store Aus - - Download- $179 plus they imply this is only for students?
Downloaded Win10 from Microsoft.  No key needed.  Created bootable USB.  Followed instructions from neat and started on the mac side.  Successfully installed WIN10 without a key.  I believe a month and it will nag for a key.  Deal with that then.

MAC SIDE 
Hold "Option" key down and power up -> Choose MAC OS disk
It offered some upgrades - accepted.  Incl a warning that an EFI change would be made.
OK

It down loaded Sierra OS but would not install it.  It said it was running on batteries when in fact the battery was 100% stuffed and was actually on power.  Gave up.
12-08-2017 Update - After replacing battery - > completed the upgrade.

Batteries
Official Apple   $189
https://support.apple.com/en-au/mac/repair/service

Aussie shop - Clickspot $149 for a 55WH.
https://www.clickspot.com.au//apple-mac-accessories/batteries/macbook-air/macbook-air-13-2010-2014-battery-replacement

Aussie shop - Batteryman  $
http://www.au-battery-man.com/replacement-for-apple-macbook-air-13-inch-a1369-a1466-laptop-battery-7-p-5475.html?zenid=a650d103adbdcd46b194940cc8a9e7f8
Model: #5475 Battery Type: Li-ion Voltage: 7.30V Capacity: 50WH
50 WH / 7.30V = 6.8AH = 6800mAH

Ebay hmm  $69

 Battery Change Instructions

Battery Change Instructions Click

Calibration of the battery

Getting ready.
Antistatic work bench.
Upside down macbook air
New battery
Most importantly - special screw drivers.  They came with the pack

This is a "pentalobe" screw driver.

Macbook open.
New battery to the right.

This is the battery clip.  the instructions referenced above had the removal of this before removing the battery.  The wires are quite thick and stiff compared to the size of the connector.  I think better to unscrew the battery and partially lift it out, then hold this connector down so it pulls out flat and just pull it out with the battery.

Did a bit of a clan up.  A fair bit of lint and dust.  I'm not super enthusiastic about compressed air.  Like a leaf blower, it can just rearrange things.  Picked the gunk off the CPU fan with tweezers.

Here it is with no battery