[HELP] MK809iv (RK3188) bricked!

I have a MK809iv (RK3188) TV stick, it got bricked. I searched the internet and tried many methods to recover it, but failed, please help if you know a better solution.

I used RKBatchTool to restore it, and got a blue square, but after I click "restore" button, it failed at "download boot fail"

Code:

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22:30:27 985        **********Restore Start Total<1>**********
22:30:27 985        <Layer 2-1> Download Boot Start
22:30:33 106        <LAYER 2-1> ERROR:Boot_VendorRequest-->DeviceIoControl failed,Total(12290),Sended(4096),bRet(1),err(0)
22:30:33 106        <LAYER 2-1> ERROR:DownloadBoot-->Boot_VendorRequest471 failed,index(0)
22:30:33 110        <Layer 2-1> Download Boot Fail
22:30:33 112        **********Restore Done Success<0> Fail<1> Time<5125>ms**********

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I also tried RK Android Tool, my stick is loaded as "Found one MASKROM Device". I played around the tool, but every time it failed at the same reason "Download Boot Fail".

I have no ideas, anyone please help!