Dear Robert,
Thanks for responding and so quickly!
I haven't used any third party power adapters, I have two Astaks - 6" and 5", so I used the cable from my smaller device.
I've tried everything you suggested (hard reset, battery removal) - unfortunately nothing helped.
The picture on the screen remains the same (showing "low battery" message), no indication of life of any kind.
It looks like this battery is dead. If it is - is there a place where I can buy a replacement?
I live in Canada.
Thank you again for your help, you guys have the best support ever!