Sounds defective, you should contact Daly for a replacement (not an uncommon occurrence with Daly).I payed $600Au for the 8s 400a bms so Not saving money at all, there are sadly no other options in that current range that i know of that are higher quality if there were id happily pay $1000 for something rock solid reliable. Daly has said light board should activate bms if in sleep mode but it does not. They also said to set timer to 65535 to disable sleep mode. i will try that. I did try 65535 once in the past and it shutdown the bms and took me days to re activate so thats why i went to the 15300 option but this time it seems to have saved the setting and remained active for now.
I hope you used a credit card.
Electrodacus with a high current relay might be a better choice for 24v at 400 amps. Or a Chargery.