There's maybe a couple of zip files for some testing in this thread and a heap of signal code but I don't know if they are appropriate for your mount and I didn't download the zip file but I will sign up to get it and have a look later.
None of this may be applicable to your mount and will require you to be down south to check unless you strip the card out and I know how impractical that is without the machine but it may help..
https://www.cloudynights.com/topic/8...pcb-schematic/
I have searched online for schematics and information, as you mentioned, not easy (impossible) to get though I may know a few sites, no harm in trying even if I do turn up empty handed.
And this if it shows up:
https://inter-static.skywatcher.com/...ommand_set.pdf
http://www.skywatcher.com/download/m...n-development/