We can fix it with upgrade or reinstal original stock rom for all of problem inside softwares Acer Liquid Z520.
More problem around softwares :
Forget email / gmail login
Stuck on loop
Dead phone after wipe
Dead after installer not suitable apk file
We must have been all need the files for flashing and repair Acer Liquid Z520 :
Flashtool Versi 5 | latest version
Mtk droid tool and root
MT6582 usb driver and vcom driver
Stock Rom Original Acer (Z520 dual sim)
|Stock Rom Acer Liquid Z520 flashing done|
Extracted Stock rom Acer Z520
Run The SP Flash tool.exe
Insert Scatter Loading file => input => MT6582_Android_scatter.txt
Click Download button in SP flash Tool Aplication
Turn Off Acer Z520
Do not Insert Battary
Press Volume Down and then Insert USB to Computer
Wait until really done.
Now can look the image how it run with sp flash tool flashing...