I'm not sure what state your 4215 was in prior to the failure, or at what point in the boot process you are getting the kernel error. You can perform a complete system re-image using either the 4.1(4) or the 5.1(2) system image available on CCO. This will overwrite all configuration settings as well, so you will need to reconfigure the appliance afterwards. Instructions for using the system images can be found in the associated readme files.
Another option is to manually recover the appliance using the Recovery Partition if you get to that point (GRUB boot menu) in the boot process. This option will maintain some, but not all, of your network settings. If you get to the menu, select the second option to recover the system. It will reboot several times while imaging, and should stop at the login prompt when it is finished.
Let me know if you are still having problems after trying one of these recovery methods.
-Rusty
