i bought the z3xPRO and want to repair IMEI but failed at patching certi

my model is G850W
and the phone imei is unknown
then i write the new imei with G730 model selected
but it’s no network
and i check *#0011# said IMEI certi:FAIL,-2
and i tried use s6 patching certi and said ztool error.
what can i do for next?

i saw someone using version z2xpro21.3 and did it.
may i know where can i download it?