Tallos 5 is a mining and construction planet where the Fire Lord once worked before he was corrupted.
Though not much is revealed about Tallos 5 other than it's connection with Fire Lord and his minions. During HF005, it was revealed that Stormer may have met Fire Lord before his augmentation which leads us to believe that Hero Factory may have some direct connection with Tallos 5.
Either those who run the mines on Tallos 5 or Hero Factory itself allowed the invention of augments being implanted in the hands of the miners. The augments would allow the miner to work longer hours without having to recharge back at their base. This desperate means of saving money and increasing production became Tallos 5's worst nightmare when the worker who is now known as Fire Lord along with several other innocents were the first test subjects of this augmentation. The miners' bodies could not handle the intense amount of energy running through their bodies which affect their internal systems.
After adjusting to the new power, Fire Lord realized that he would never be able to stop absorbing fuel cells and left Tallos 5 to find more power.