Default bootloop after install cm 10.1.2


i installed cm 10.2 on my xtz wifi 32gb. because of missing cifs.ko module i tried to downgrade to 10.1.2 using cwm (install zip). now i've a bootloop, i see the cm logo since 1 1/2 hours. i think the problem is, i've forgotten to wipe the data before install cm 10.1.2. i can't boot into cwm, when i shutdown the tablet with power+vol+ there is no sony logo. the first logo i see is the free xperia logo.


i can boot into fastboot. can i fix the error this way (wipe or anything else)?