Hi Dave,
Don't put yourself down. You have managed to post on here several times and got your original unit working fine, so things aren't so bad!
The reason nothing happens when you click on 'Check for Updates' with your tablet connected to PAW WiFi is because PAW has
no Internet connection. To obtain updates direct from the internet, your PAW has to be connected to a router with an Ethernet cable then powered up and left for about 20 minutes to allow it to search for and find the PAW download website. The best way to 'update' these days, however, is by using a USB memory stick to transfer an update file from the internet to your PilotAware. Fortunately you are already running PAW Version 20160820 as this is the earliest version of PilotAware which supports USB update. I will try to explain how to do it using simple steps.
First, you need a USB Memory stick - most sticks will work, but there are a couple of (slightly technical) issues to do with the spec of the USB stick, which I don't want to confuse you with here. The best advice is, if you already have a stick, just give it a try.
Next you need to download the 'Update file' from
www.pilotaware.lode.co.uk onto your computer and transfer it to the 'Root' of the memory stick (i.e. Don't put it inside a folder). Also, you must NOT change it's name.
Power up your PilotAware as normal and connect to it using your tablet via 192.168.1.1.
Now insert the USB stick into your spare USB port, go to the 'Update' tab and click on 'Check for Updates'. This time after about 30 seconds or so, the new update (20170721) should appear, together with a 'live' (i.e. not 'greyed out') 'Install' button. Click this and the update should install in a few minutes and the unit will reboot automatically.
Check you are logged back onto the PAW Wifi, then go back in to 192.168.1.1 (you may have to reset this manually as PAW sometimes adds "/update.cgi' or similar to the end of the 192.168.1.1 bit).
Finally check on the Home and Configure Screens that PAW is now showing the new version.
Hope this helps. Let me know how you get on.
Re your licence renewal, you should have got an e-mail about that. If you haven't received it, check your 'spam' box.
Regards
Peter