kindle pw2 brick

I think my one is pw2 and I downgrade to 5.4.3.2 and install duokan..

Duokan is not run and I thought it was not install and I reset my device..

At first, it looks good but it stuck at the end of loading and computer can't recognize that I plug kindle..

So.. I can't put any bin file like rescue pack or firmware

Anyone know how to fix this?

:help:

(Sorry for my English skill... I'm not living in English speaking country...)