xperia go - light rom needed!

I tried to install http://ift.tt/1VnY6Yk
but after flashing boot.img
the phone will lock on "sony" after starting

then I tried to again flash an official ROM
6.2.a.1.100

but it said me the internal memory has not enough memory

I know that my internal memory had about 400Mb , but this isn't enough

so now

I can boot into both flashmode and fastboot

fastboot is stable but flashmode will exit after about 30 sec automaticlly

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so I tried to install ftf file with unzip it and use fastboot mode. but the problem about the internal memory again stopped me

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so if I had a light ROM to flash it I can free up my memory
or if there is any other way...

I had an SD card on my xperia go and it is empty, but I don't know how to use it in fastboot mode

anybody can help me ?

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