3300 MRL keeps giving battery warnings and won't run on Automatic. Batteries are fine. I believe it's the SEMNA card as this has the charger on it that isn't doing it's job anymore. I'm leaning towards card replacement. Anyone experienced this issue yet?

Presume you're aware that you have to press yellow button to activate battery charging. If so change card.

Hi
Are you on the last version of 3300 (Bionic7) ?

If yes there's an issue with the SEM SW, if your version of sw SEM is under 2.8 (in CF12 PA4 you must see 280)
In that case update or replace the SEM and also the battery.

If older version of 3300 (rel2, rel4), if the voltage of your battery is low, the SEM can't charge.
The SEM is just able to keep the charge on top.