Growatt inverter not picking up battery

I have a 5kva growatt inverter running well for the 16 months. for the last 2 weeks we were getting an error 56 on the inverter when we reset (power down and power up) the inverter the error clears and everything works again. Today we got the error 56 code again i reset the inverter and it started working but i have a flashing warning light on setting 19. The inverter is using the grid and solar at the moment it is not even picking up the battery. I checked on the shinephone app and it looks like the battery depleted as according to the App it is sitting at 10%. Is there a way to check the battery and what percentage charge it has left and how do we get the battery recharged externally? or is there a company that offers this service. Please help