Well it turned out I wasn't very good at removing the solder, it just wouldn't come out of the holes.
I ended up snipping the legs and replacing the transistor.
Afterwards, all the LED's lit up fine and the voltages were good.
Fitting the second PCB was straight forward with no mistakes this time and its LED's lit and had good voltages.
Powered it up and worked fine.
I even have the problem with the sound and jack plug I mentioned earlier fixed, it was definitely a loose wire which is properly soldered now.
The amp sounds fantastic now, seeing as I loved the sound before the upgrade, not sure how much of an improvement it is, but will have to listen to it for a while. The bass did sound a bit tighter though.
