Low Battery warning could be the Key Battery is low in charge. The later keys have a CR2032 internal battery, and not a re-chargable type. My SD4 was showing low battery messages, I changed the key battery, then the main battery, as it was charging at 16.5 volts. Hope that helps you.

Had email to say new post to Chrism551 thread……a few interesting posts….is car better now…?

Replying to Jagracer : 16.5 volts charging seems a bit too high…..suggesting alternator problem….??
Have my own battery problem at mo : Thursday last we went shopping….wife bought frozen food…so with temperature being 27deg I had cool-box running in the boot…..I left it connected whilst we went to have bit of lunch…..40 mins later came back to car…..couldn’t open it …thought it was keyfob…wife tried her spare one…..no good. Opened car with the key via left-hand door….first time ever. Started car with my trusty JS 3000 booster…..charging well….14v. Exide battery that I fitted January ‘24 went completely dead after max 40 mins of discharge at 6amps draw…..! We were parked walking distance from à French Halfords….Norauto who said that they could get me a new Varta next day. They didn’t….have to collect Monday………present Exide goes flat after few minutes……..doubt it’s a system drain.. but will see.
As an aside I have thé ‘over 20deg’ occasional stuttering back…..as per my thread Home/Technical ….top of page.
Interesting link my IanMetro about Aisin transmission…clever stuff……. FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.

A quick update on this. It's 2 weeks just about since I fitted a new battery and since then I have had no more warning messages come up on the info screen so I take that as fixed. Interesting considering it warned of low battery but the car started perfectly.
On the second issue of the car suddenly losing power in warm weather, like limp mode or severely reduced power, with no codes recorded, I did fit a new filter, only had a MANN one available to replace the Luften filter fitted. To date the car hasn't lost power since, even on the hottest days it seems to run the same way, and I have driven it hard to try and force the issue to re appear but so far it seems OK.