USB HID mode (USB Recovery mode) has tools available from Freescale that can use this mode, but they only run in Windows (sb_loader and MfgTools). There are plans for a custom repair tool that uses this mode, but it is in progress.
Try holding the power button for 30 seconds, then release, then press again, to get back to diags or main boot. Because main is damaged, you need to get back to diag mode again. It can be repaired from there.