If you are experiencing overheating, the best way to remedy this is to reapply the thermal paste underneath the heatsink. This video will show you how to accomplish this with a lint-free cloth (or your finger) and get back to hashing in no time!
If you are ever in Overheat Mode, it will need to be manually disabled in the settings of your Bitaxe. This is a precaution to prevent further damage in case the bitaxe was ever powered without the heatsink.