My nokia lumia 1020 dosent turn on its totally dead

one week ago I charged my phone and started using it, after some time it was unable to detect network and in sim settings it showed sim error. I thought a restart or reboot may fix it so i turned off the phone and waited for some time, then i tried to turn it on but it wont start at all even the battery was 70% charged and the phone was working well, now i have tried all hard reset options but none of them worked, i heve also dismantled the phone and found all connections ok, even Windows recovery tool is unable to detect the device.