it's bricked, you tried to install custom recovery without unlocking bootloader?

you can revive it using that tutorial. leave the battery in in order to get to s/w upgrade screen, but before that, you need drivers (and if your computer isn't detecting it in s/w mode, the drivers aren't installed)
To install custom roms on O4x:

1. upgrade to jb
2. root
3. unlock bootloader
4. flash custom recovery (cwm)
5. flash roms
6. if you encounter any issues, search, they've been answered already.

Got issues with RIL/IMEI/BASEBAND on custom 4.2, 4.3 or 4.4 ROMs on p880? Click me for possible solution!