Android head unit lost all its settings!

[Stephen29]

I have a 10" Android head unit, similar to the 'Pluscenter' ones
Toyota Estima | 2006-2016 | Android 13 | Car Stereo Head Unit | Pluscenter

I havent used the car for about a week, and today I find the Android head unit has lost all its settings and the extra apps I installed etc.
Nor does it have saved screenshots
Its like it has reset to defaults, rather than just lost power
They dont seem to get any power off 'ignition' is off and no Battery backup ?
(just losing power wouldnt cause it to lose settings etc that are on non-volatile storage, so seem to have done a full reset !?)

Anyone else seen that ?

Now need to spend an hour or two reinstalling and setting up stuff 😞

[Stephen29]

Now reinstalled stuff
Hope it doesn't suddenly lose it all again
Still cant understand how/why

The 'built in' Here WeGo navigation app has lost its maps
and trying to update them gives "Couldn't download"  ...??? weird
Appstore says the app isnt compatible with my device anymore ?
 

[JohnGW]

Maybe a geographic restriction? 

Due to a vampire drain of my Battery, i have fitted a remote batery switch so every start is a full boot up of the Android unit but all apps remain. Even the radio stations.