TF300t bricked, no fastboot, wrong recovery
Autoupdates brick a lot of Transformers when on CM.  Bad sounding situation, in my opinion.  Fastboot and ADB are the only ways you could recover your device if you have a bad bootloader and recovery.  Have you tried holding Vol-Down while resetting with a paperclip?  That should force fastboot.  If not, we can try adb.

Do you have adb access while your tablet is plugged in to your computer?  Turn on your tablet so it is in recovery, and on your computer, run adb devices to see if your tablet is available. If so, adb -d reboot-bootloader should force your device to reboot into fastboot.  From there, run fastboot erase x where x is:

system
recovery
userdata
boot
misc
cache

and then after that, you can flash your files and/or restore your .blob files.