I wouldn't really recommend trying to fix yourself. Removing/replacing heatsinks and chips on these hashboards is not easy, and without lots of practice, you'd probably just create more issues.

You can search back through this thread to find some potential remedies that may get the board up at least temporarily. Changing the temperature and/or orientation of the miner can sometimes close broken solder joints or open shorts caused by excess solder on the board. In my experience, these are the most likely causes.

Best option is to find an experienced repair shop.