[HELP] Can't enter flashmode/recovery mode/fastboot mode [e2306] [MM] {UB}

Well, i've flashed the ftf file downloaded directly from xperifirm {E2306_26.3.A.0.131_R2C_Customized GEL_1294-3902}
then, i've try to install root (following a tutorial for this device and this comp.) but i could not enter to FASTBOOT MODE
try using:
- (vol+) + (plug the phone)
-(power btn) + (vol+) + (plug the phone)
-(power btn) + (vol+) + (vol-) + (plug the device)
and the only thing that happened is: -Vibrate + sony logo ---> normal boot
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Then i try to enter fastboot using the adb command {ADB REBOOT-BOOTLOADER}
but it just reboot normally (sony logo and then start normally)
[[ADB do recognize my device and all drivers were properly installed; but can't enter to fastboot mode]]
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I've try to reflash my device again, but then i couldn't be able to enter to flashmode
{ with the device off; press vol- and then connect to usb}
after several attempts using - [(power btn) + (vol-)] i entered flashmode and reflash my device...
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then i activate dev mode: [usb debuggin and OEM UNLOCK]
and try to get to fastboot mode, but the same results...
i got my device recognized by {ADB DEVICES}
but can't get fastboot
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Then the user who's helping me told me to reflash using this config
[in excludes section check all except AMSS_FSG, AMS_FS1, AMS_FS2,BOOT DELIVERY, KERNEL. Don't check anything else.]
But i can't get flashmode now... i try all the combinations, try in ubuntu 16, and windows 10... but nothing
the device starts normally nothing wrong.... except well, i can't enter any -mode- now...
any help?
Thanks