Cyclone V E Dev Kit; Erased flash, now Max V seems malfunctioning

[RadicalExponent]

Hey,

I've been working with the Cyclone V E Dev Kit for half a year now, mainly making changes to an already existing, bigger project.
In a bit of a careless move, I decided that, to solve a problem I was faced with, might be taken care of by erasing the flash memory.
So in the Nios II Command Shell (Quartus Prime 18.0) (standard) I typed the command:

  nios2-flash-programmer -b 0x0 --erase-all

Ever since, the red LED (D17) is on and I am left wondering what the horse happened.
Efforts to restore the board to factory settings (following the user guide Appendix A) were futile.
Programming the FPGA as well as the MAX V CPLD (using the Programmer GUI) mostly works but sometimes results in an error message (appended as ProgrammerError jpg).

Programming the flash, with the restore.sh script to restore factory settings, only pauses the processor and never starts actual programming (image FlashProgramming jpg).

Programming the FPGA and Flash with custom .sof / .flash file works fine.
Configuring the FPGA from flash (via FPP) on the other hand seems to not work anymore after reseting the board/MAX V.

I would be very glad hint on what's going on on the board (did I kill a part of the MAX?)
What did the erase command do?
Could it have been the cause for all of this?

In steady hope of some saving grace for my board I remain,
Felix