SM-G920F mdm does not allow factory reset / download mode

Code:

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Operation: Reset FRP UFS
Selected model: SM-G920F
Selected port: COM14 USB Serial Port
Software version: 34.3

Hold 'Vol down' and press 'POWER ON' for 2-3 seconds
Checking phone at COM14 OK
Phone detected, do not release 'Vol down'
Reading data from phone... OK
Release 'Vol down' now
Comparing selected model... match (G920F)
Setup connection... OK
Reseting FRP... OK
Rebooting phone... OK
Reset FRP done

Done with Samsung Tool PRO v.34.3

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Code:

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Searching Samsung modem... detected COM40
Reading phone info...
Model: SM-G920F
AP version: G920FXXU6ERF5
CSC version: G920FOXX6ERF2
CP version: G920FXXU6ERF6
Product code: ROM
Phone SN: RF8H31PNQNA
IMEI: 357011000ddddd
Unique number: 02160271DB061005
Reading IMEI... OK
IMEI: 3570110000ddddd (SIGN: UNKNOWN)

Done with Samsung Tool PRO v.34.3

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Code:

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Searching phone and switching to flash mode... OK
Done with Samsung Tool PRO v.34.3

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download mode even not possible with JIG (even batt removed)

what to try next???