Lacoste

I have installed a Goodwe inverter GW5048 together with 5kw Pylontech Lithium battery around February2023 and set up on backup mode with 60% DOD. Everything was working fine until yesterday 19 April 2023 when everything changed: There was load eskom shedding in our area from 18h00 until 22h00. The SOC moved from 100% to 74% when the eskom power was restored and suddenly the SOC dropped to 41%. The batteries were charged until 46% when another bout of eskom load shedding came about around 02h00 am until 06h00 when the SOC moved from 46% until 41% but suddenly when the eskom power came back at 06h00, the SOC dropped to zero % and now it's been 1hour with eskom working but the batteries are not charging. All the power goes to the house and nothing goes to the battery. What could the problem be and how can I solve it?