Hmm - I did spot that the Amazon reseller I bought this from has stopped selling them so have contacted their support team to see what they say.
I did try using the S905.aarch64-7.0.2.008 file to update it, using a toothpick to hit the button on the underside of the box. It looked like it was working then went into recovery with an error message (something like expecting string, got value type 2). If there are any standard fixes for this error, be great if you can let me know. Otherwise will wait and see what Wetek come back to me with.
Cheers,
Gavin