I think it's more of a hardware and temperature problem than a firmware problem. I had the same problem as you, the miner didn't work for more than 2 hours so I made a mod to cool the back of the miner because only the back reached 50°C (122°F) without counting the temperature of the main chip. I checked it with my infrared thermometer and when it was completely closed some component overheated and to avoid problems it restarted for protection.