Kobo Glo HD mac adress and charging problem

Hi guys and sorry for my English. Now I have this book and it has a couple of problems. 1)- the MAC Address field is empty. 2) - Charging is only up to 80 percent.
Factory reset did not help.
Firmware update did not help.
Аfter flashing SD-card image,I saw the mac adress but all the same "no wifi network found". Next update and i saw again mac an empty.
The battery shows that it is charging, but in reality the charge does not rise above 80% for the last night and I'm not sure that it is charging at all now, only discharged.
Maybe someone has any ideas?...
Thanks