So I eventually managed to get my Touch working after a lot of faffing around due to my “little bit of knowledge” and not fully reading the instructions.
If I had followed the links and advice given by PeterT and DNSB and followed the instructions to the letter it would have been okay..
My first mistake was that the Touch, as bought from Ebay, had an 8GB microSD containing the Android operating system instead of the usual 2GB containing the Kobo OS. So I took a 2GB SD I had and wrote the kobo image to that and it would seem to run but wouldn’t update by wireless or PC. I tried copying the update files to the .kobo folder but this made no difference.
My second mistake was thinking that there was a problem with my 2GB SD as there had been an error message when writing the image about insufficient space. So I formatted a 8GB SD and followed the exact process as before and got exactly the same result. Of course I had to repeat it several times, as you do, in case I had slipped up, it had become corrupt, etc.
Eventually as usual if it doesn’t work, you go back and read the instructions fully. Going back to the instructions,
Kobo Glo Memory Upgrade Guide ( it is a general guide and works with other models), I read this fully this time and saw about tweaking the partitions after writing the image. I did this, then copied the update files to the .kobo directory and after refitting inside the Touch and powered on it all worked.
So thanks again everyone, I’m off to read some books.