The system can be restored by Dell indications with USB, as long as the original machine bios structure corruption is at a certain degree… when an IC is flashed with 20kb instead of 8Mb, for sure no regular OEM regular methods will work.
Backups can be made with an hardware programmer connected directly to the IC or by software (InsydeH2O), Intel FPT tool v9 is also an alternative sice its an Intel platform.
Further reading about Intel tools and ME FW Engine related:
Intel (Conv.Sec.) Management Engine: Drivers, Firmware and Tools (2-15) - Special Topics / Intel Management Engine - Win-Raid Forum