... I was just checking, if you bought phone from GearBest or similar,
you may have Chinese "N" model of the Phab 1 phone.
in that case, try flashing with this :
PB1-750N_USR_S000384_1603250635_R5.1_PRC_CN
If still the same, imei empty, no baseband ... well, that will be tricky.
b.r.
Alex