Maybe it's a hardware brick. Try this:
1.- Open flashtool
2.- Push at the same time for 15 seconds: power, home, volume + & -
3.- put in the usb
4.- flash a stock rom
Enviado desde mi ZP900 usando Tapatalk 2
I've also tried pressing power + vol - and pwr +vol + and connect the cable, but nothing happens. No device isfound.