Picked up from Ebay for £12.50, the fault was "Console turns on but doesn't load ds games, and touch screen doesn't seem to work,".
Makes me a bit sad, but this fix was literally clean the DS cart port with IPA, and run a DS cart in and out. There was also some gunk inside the device, which again, just needed cleaning.
The touch screen, after testing, was fine too. Maybe it was the ribbon that needed re-seating, and I did completely take the DS Lite apart and re-shell it (originally it was red with a LOT of stickers) - I feel like the re-shell has a bit of a Star Wars dark side vibe!