Thank you for replying, this is exactly the response I was hoping for. To take your points one at a time:-
Yes I am using the cable that came with it.
There maybe a problem with the cable, but in frustration I have tried to power it up with the cable disconnect but it still won’t, at the time of the fault. I am going through some of your points outside the car, even though the battery is low it still powers up.
I understand there is no need to start the engine but in those cases I did.
As I have said, when the fault occurs it still will not power up with the cable disconnected.
It isn’t connected to the Garmin App and Bluetooth is off.
When the fault has occurred it has been off for more than 5 mins whilst navigating using signposts then trying it again.
As far as the spelling of places we are using a French map. We have had to attempt to use this at times.
The 51 is set for France, to use the French roads.
There is the option of changing to French language but our French is not good enough to quickly interpret instructions. But would it only be spoken French?
I haven’t connected it to Garmin Express for updates, but villages and towns which have been in existence for many years would not have needed updating. Maybe new roundabouts, no entry streets which could change.
As I have said we use a French map and use the spelling from that.
In our situation, where we are on holiday, we don’t always know where we want to go when we set off.

Just to repeat my two main concerns 1) Unable to power up 2) Can’t use the keyboard to complete the spelling of a word as it is not in the suggestion bar and further letters are not highlighted, why is it we can only go where Garmin wants us to go?

However, thanks aspirin624 for taking the trouble to reply, I much appreciate it.