mk809 ii stay at boot screen

[pepede]

Hi i have mk809 ii. When its powered it boots and then hangs on boot screen with animated " rkbox " . Somewhere i found tutorial about flashing this device. Unfortunately win 7 64bit isnt detecting this dongle- there is no beep, or changes in device manager. Its my 1st dongle probably with stock android so i dont have experience with flashing it and i may do sth wrong. I just want to make it working back.
Regards

[pepede]

Any help? Idea?

[HaSuKrOnOs]

Use a 5v/2a charger, be careful of poor quality chargers.

[pepede]

No, power supply is right. It has 5v/2a. Second dongle is powered well with it.