What do Bitmain miner's signal lights mean?

Fault light (red) and Normal light (green)

✔ When the miner is running well, the green light flashes and the red light does not.

✘ If the red light flashes, there are two possibilities:

1. High-temperature alert.

• High-temperature alert and protection

2. The network is off. Try to reconnect to the internet. 

✘ If the green light is on continually, there are two possibilities:

1. Can't connect to the internet. 

• Can't connect to the internet or can't find the IP

2. IP issue. 

• How to reset miner to factory settings

✘ If both the green light and red light are off, the fan might be bad:

Replace with a good fan to test. 

✘ If the red light flashes but the green light does not, there might be IP conflict:

• Where and how to use IP reporter
• How to set a static IP address
• Bulk management tools: 

1. Antpool：https://www.antpool.com/download.htm?m=tools
2. BTC.com：https://pool.btc.com/tools

Ethernet port light

✔ When the miner is running well, the yellow light is on and the green light flashes.

✘ If both lights are off, there are three possibilities:

1. The network cable is not plugged in well. Re-plug it. 
2. The control board is bad. Replace with a good one to test. 
3. The switch is not powered. Power on the switch.

 Source: https://support.bitmain.com/hc/en-us/articles/360018826774-What-do-miner-s-signal-lights-mean-