[XDA-University] demkantor:
[MENTION=5318017]knifey_au[/MENTION]

ok so I downloaded and took a look at the file you want to flash

assert(getprop("ro.product.device") == "roamer2" ||
getprop("ro.build.product") == "roamer2");
assert(getprop("ro.product.name") == "P752D01_Cosmote_GR");

these are the three lines that need to be the same in build prop, but in truth if you havent a custom recovery than it may still see your product info in your recovery as you have the stock kernel=stock recovery

and these are all the lines in the new build.prop you are trying to flash

# begin build properties
# autogenerated by buildinfo.sh
ro.build.id=GRK39F
ro.build.display.id=ZTE Kis LiteV1.0.0B01
ro.build.version.incremental=20130427.041932.31486
ro.build.version.sdk=10
ro.build.version.codename=REL
ro.build.version.release=2.3.6
ro.build.date=Sat Apr 27 04:30:41 CST 2013
ro.build.date.utc=1367008241
ro.build.type=user
ro.build.user=
ro.build.host=zte
ro.build.tags=release-keys
ro.product.model=ZTE Kis Lite
ro.product.brand=ZTE
ro.product.name=P752D01_Cosmote_GR
ro.product.device=roamer2
ro.product.board=roamer2
ro.product.cpu.abi=armeabi-v7a
ro.product.cpu.abi2=armeabi
ro.product.manufacturer=ZTE
ro.product.locale.language=el
ro.product.locale.region=GR
ro.wifi.channels=
ro.board.platform=msm7k
# ro.build.product is obsolete; use ro.product.device
ro.build.product=roamer2
# Do not try to parse ro.build.description or .fingerprint
ro.build.description=P752D01_Cosmote_GR-user 2.3.6 GRK39F 20130427.041932.31486 release-keys
ro.build.fingerprint=ZTE/P752D01_Cosmote_GR/roamer2:2.3.6/GRK39F/20130427.041932.31486:user/release-keys
# end build properties
#
# system.prop for surf
#

rild.libpath=/system/lib/libril-qc-1.so
rild.libargs=-d /dev/smd0
persist.rild.nitz_plmn=
persist.rild.nitz_long_ons_0=
persist.rild.nitz_long_ons_1=
persist.rild.nitz_long_ons_2=
persist.rild.nitz_long_ons_3=
persist.rild.nitz_short_ons_0=
persist.rild.nitz_short_ons_1=
persist.rild.nitz_short_ons_2=
persist.rild.nitz_short_ons_3=
ril.subscription.types=NV,RUIM
DEVICE_PROVISIONED=1
debug.sf.hw=1
debug.composition.7x27A.type=mdp
debug.composition.7x25A.type=mdp
dalvik.vm.heapsize=40m

#
# system props for the cne module
#
persist.cne.UseCne=none
persist.cne.bat.range.low.med=30
persist.cne.bat.range.med.high=60
persist.cne.loc.policy.op=/system/etc/OperatorPolicy.xml
persist.cne.loc.policy.user=/system/etc/UserPolicy.xml
persist.cne.bwbased.rat.sel=false
persist.cne.snsr.based.rat.mgt=false
persist.cne.bat.based.rat.mgt=false
persist.cne.rat.acq.time.out=30000
persist.cne.rat.acq.retry.tout=0
persist.cne.fmc.mode=false
persist.cne.fmc.init.time.out=30
persist.cne.fmc.comm.time.out=130
persist.cne.fmc.retry=false

#
# system props for the MM modules
#
media.stagefright.enable-player=true
media.stagefright.enable-meta=false
media.stagefright.enable-scan=true
media.stagefright.enable-http=true
media.stagefright.enable-fma2dp=true
media.stagefright.enable-aac=true
media.stagefright.enable-qcp=true

#
# system prop for opengles version
#
ro.opengles.version=131072

#
# system props for the data modules
#
ro.use_data_netmgrd=true
persist.data.ds_fmc_app.mode=0

#
# system props for IMS module
#
persist.ims.regmanager.mode=0

#
# system prop for requesting Master role in incoming Bluetooth connection.
#
ro.bluetooth.request.master=true

#
# system prop for Bluetooth FTP profile
#
ro.qualcomm.bluetooth.ftp=false

#
# system prop for Bluetooth SAP profile
#
ro.qualcomm.bluetooth.sap=false

#
# system prop for Bluetooth Auto connect for remote initated connections
#
ro.bluetooth.remote.autoconnect=true

#
#system property for Bluetooth discoverability timeout in seconds
#0: Always discoverable
debug.bt.discoverable_time=0

#
# System prop to enable/disable OMH. Enabled by default
#
persist.omh.enabled=1

#System prop to enable ehrpd capability
ro.config.ehrpd=true

# System property for cabl
ro.qualcomm.cabl=1

#
#System prop to determine availability of
#analog fm path
#
ro.fm.analogpath.supported=true

#
#System property for FM transmitter
#
ro.fm.transmitter=false
#
#System property for single instance recording
#
ro.fm.mulinst.recording.support=false
#
#System property for msm
#
ro.hw_plat=7x27a

#
#System property for Power Saving
#
persist.radio.add_power_save=1

#
# ADDITIONAL_BUILD_PROPERTIES
#
ro.com.google.clientidbase=android-zte
ro.com.google.clientidbase.yt=android-zte
ro.com.google.clientidbase.am=android-tmobile-{country}
ro.com.google.clientidbase.ms=android-tmobile-{country}
ro.com.google.clientidbase.gmm=android-zte
ro.build.baseband_version=P752D01_Cosmote_GRB01
ro.build.sw_internal_version=COS_GR_P752D01V1.0.0B01
ro.build.baseband_version=P752D01_EUROPEB01
ro.build.sw_internal_version=P752D01_EUROPEV1.0.0B07
ro.build.baseband_version=P752D03B01
ro.build.software_version=GENERIC_P752D03V1.0.0B01
ro.build.sw_internal_version=GENERIC_P752D03V1.0.0B01
ro.camera.intrplt.2mpto3mp=true
ro.build.baseband_version=V766B01
ro.build.software_version=GB_P752A10V0.0.0B01
ro.build.sw_internal_version=GB_P752A10V0.0.0B01
ro.config.ringtone=COSMOTE_1_BACKRINGTONE_A_2.mp3
ro.config.notification_sound=F1_New_SMS.ogg
persist.sys.timezone=Europe/Athens
ro.config.notification_sound=OnTheHunt.ogg
ro.config.alarm_alert=Alarm_Classic.ogg
ro.setupwizard.mode=OPTIONAL
ro.com.google.gmsversion=2.3_r11
persist.sys.usb.enable_switch=1
persist.sys.usb.linux_switch=1
persist.sys.usb.switch_pid=0x1351
persist.sys.usb.linux_pid=0x1351
persist.sys.usb.default.pid=0x83
ro.com.google.clientidbase=android-zte
ro.com.google.clientidbase.yt=android-zte
ro.com.google.clientidbase.am=android-zte
ro.com.google.clientidbase.ms=android-zte
ro.com.google.clientidbase.gmm=android-zte
ro.camera.intrplt.2mpto3mp=true
net.bt.name=Android
dalvik.vm.stack-trace-file=/data/anr/traces.txt

not sure what your current android version is but this one is 2.3.6 and should be fairly easy to build a custom recovery for your phone allowing you to flash nonstock .zips

just follow clockwork or twrp guide on how to create your own

and there is no firmware in this package, just kernel, ROM, and recovery so it should be safe enough to flash as long as you have a backup of original.

best of luck!