Hello there
Did you have your budgetphone working again ???
I had the same problem and to and the solution was to down grade the firmware it seme's to me that the firmware is corrupt.
My English is not so good so difficult for me to explain but if you still really need help I will try to explain it to you.
Your phone are not totally dead so there is hoop. I did restore 1 budget phone and a adaptor from Grandstream this way.
If you need help just let me know
Regard
MasterDigi
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