Yongnuo YN 600EX-RT - OVERHEAT Problem (error message)

I have just received the new Flash Yongnuo Speedlite 600 EX-RT from China through Ebay (received 15/07/2015). And as soon as I turn it on, an error message appears about “overheating“. The flash in unusable and I cannot access to any function. Even if I install the last firmware , the problem still remaining. This overheat problem is encountered many times, but no solution from Yongnuo ! I am very angry against them ! If you have encountered the same problem and have a solution for me, please comment