Kindle Model No. DP75SDI

Hi,

In first place, I want to ask what Kindle model is this ? I did't find DP75SDI in any list.
Inside looks like an PW2 but with SIM slot.
Problem is ( I think ) with the firmware because when I turn on, the backlight lit and kindle startup page blinks time to time.
I try to reset, holding the power button for more than 5 minutes. When I hold the power button for reset the LED blinks orange, 5 times.
I left to charge more than 24 hours, and I verify the battery voltage, and is ok.
I have usb to serial interface ( TIAO USB ) but I did't find any firmware for this model.

Any advice would be helpful.

Attached Thumbnails