Never had experience about this miner but let me try to help you.
Here's my own solution that I know might fix this issue.
- Reflash your controller (Raspberry Pis) with the correct firmware. You can find the procedure here including firmware
click me- Possible the miner is full of dust. Disassembly the miner and clean all boards and terminals from fan to board might solve the issue. Don't do this if your miner still under warranty.