So, if we assume that you made full rom_0 backup,
No damage could be made.
I said hardware should be identical, at least by factory board naming.
Flashing system.img + custpack.img cant damage anything,
Writing full rom_0 backup returns everything to previous state.
If you have phone in hands for day or two, i can assist in reflashing it,
And providing original stock rom after that operation.
*** EDIT:
found one rom, it's box backup but it works (as reported) :
MT6580_S00_EMMC_MRA58K__6.0_VFD 300_Vodafone
SPFlashTools are also included in archive. PID: V300-2BVDAU1 (Vodafone Australia)
B.r.
Alex