Someone install a modified version of kernel which has u-boot included.
This is usually used to start MeeGo/Nemo

If you have done that, you have U-Boot and you can boot your phone from SD Card having so an hope to recover it without usb cable.

To know if you have u-boot is simple.
Do you see a pinguin image and various text string during boot process ?
If not sorry you don't have u-boot installed