Thank you,
I didn't have any luck loading files onto the unit but found that if I squeezed it while turning it on it loaded normally.
I opened it up to check if something was loose, looked fine. It then started like it should and ran for a few minutes before shutting down to "System Software Missing" Message again. I managed to do an update using Garmin web-updater, the update loaded but the unit still shut down after some time.
Will have a bit more of a play with it soon but thinking its most likely caused by physical damage.

To get the RGN file do I create it by running the Map62s latest GCD update through a RGN tool? Or is there a RGN file available somewhere to download? Just want to make sure I'm actually doing it properly.