This miner is a clone version of Cheetah a1 miner and it seems their old website aisenminer.top is suspended.
I can't even find the firmware on Google for this miner.

Anyway, can you try some steps below and maybe it can solve your issue.

- Find the reset button near the SD card slot then press the button for 15 seconds then release. Test again after.

- If it doesn't work try to disassemble(I don't know exactly the miner what it looks like) and look for ribbon cables connected from the control board to hashboard. Remove them all then reattach them and also the power supply on 3 hashboard after that reattach the ribbon cable and power supply to all hashboard and control board. After that test it again.

- If the issue still persists try to check the hashboard one by one remove the ribbon cable and power supply to two hashboard then test it again. Check the kernel logs for changes and if it's running fine without the other two. If it's running fine then do the same on the other two hashboard to test which one is broken.

- Since you have many working miners why not try to take the hashboard from working miner and use it to test it on the broken miner. So that we can test if the issue is on the hashboard/program or if the 3 hashboard is broken. Also, check the power supply and maybe the power is not giving enough power that is why it's not running properly.

Take note: If these miners are still under warranty much better don't disassemble these broken units instead contact the seller if where you bought this and tell them about your issue.