MPPT Solar Panel Problems in Coachman 545

Hi, not sure if anyone can help us but we’ve got a problem with our solar panel not charging the battery. We are awaiting a replacement charger under warranty as the battery doesn’t charge on electrics, so we are currently relying on battery/gas when on site. However, we have now noticed that the solar panel charging panel (MPPT Pro) is showing as being on standby. According to the instruction manual (which is quite basic) this is because there is less than 50% charge in the battery, but we have put on another fully charged battery and it’s still showing as being on standby.  Does anybody know how we can get it off standby and back to charging? It’s driving us bonkers as I’m disabled and my husband is having to change the battery 3 or 4 times on a trip, even with a new battery.

The caravan is only 2 years old.

Many thanks in advance for any assistance.