So my battery that I ordered turned up. I didn't have any order confirmation and when I emailed the company didn't get a response. I also googled the company and they had some bad reviews so I assumed they'd stolen my cash. However two weeks later I got it.
I watched a few videos online and used the Mr fix it guide to work out how to install it and using a few tools I already had (small watch screw driver, guitar picks, tweezers, pin, plastic toothpick, pen knife and hair dryer) I was able to swap out the battery.
One thing I noticed none of the guides mentioned is when you remove the circuit board from the watch housing there are 4 little plastic spurs that drop out. These are used to secure the circuit board inside the watch housing and slot into grooves in the metal housing. However its literally impossible to get them back in when you re-assemble the watch, so I had to leave them out. Initially this didn't make any difference though I do now need to buy some adhesive to reseal the case. Also another issue I had which is worth noting is that the connectors are very small and fiddly and you must make sure they are fully plugged in otherwise the watch won't switch on. At first I thought the replacement battery was duff but then I took the watch back apart and noticed I didn't have it fully plugged in. The battery also required charging once installed, even though it had about 27% power it needed the initial kick from the charger to make it switch on.
Here's a few pictures:
First one is me removing the back off the watch (I heated it up for about 5 minutes with a hairdryer to loosen the back off):
Back off:
Two parts separated:
Circuit board out, note the old swollen battery:
Battery removed from circuit board, it was stuck down with a bit of glue, which thankfully remained sticky for the new battery:
So far the battery seems a lot better and when I went to charge my watch last night I had 38% power left, which is opposed to the watch running out by about 6 pm with the old battery. The main problem is that the watch circuit board is very loose and moves about, so I need to buy some more adhesive to re-secure it, its also possible that the spurs not being re-fitted are causing this. Also the button on the watch isn't functioning, mainly because you need to precisely line up the button with the circuit board, which I obviously haven't done, but I can easily get by without the button. I'll do some more fiddling when I get the adhesive and may even make another attempt at re-fitting the spurs.
I don't think google have given up on Android Wear. There's the LG Sport and Style and also the Huawei Watch 2. Only trouble is barring the cut down feature wise LG Style these are very big watches.