Okay - I give up...
Current situation is...
Turn on box = "NO CA OR IMAGE - 2ND FAILED" with a picture, followed by "BIOS NO CA FOUND"
Connect with optiflash v.2.0.0 posted above (even though it says v.1.0.0 when loaded) = connects to DM but fails to give IP
Connect with optiflash v.1.0.5 -- does give me an IP, it sends SSL #79 to the DM but whichever SSL I then upload to it, it fails to read on reboot
Connect with Dreamup - hangs when connecting to DM
My diagnosis faulty sim, or sim reader in box, most likely SIM. Tomorrow I'll swop with a SIM from my box to see if the problem migrates to my box / cures my dad's box.