The stock SBF/FXZ for the AT&T Atrix 2 2.3.5 has been found by daywalker04 on XDA. It will help recover soft-bricks and phones with major errors. Using this will wipe your system, user data and settings and will return you to a full retail/stock state.
Android 2.3.5 ---- Blur_Version.55.11.16.MB865.ATT.en.US
Gingerbread 2.3.5 for ATRIX 2 MB865 AT&T USA
See this post for a direct download link: [Fastboot Files] Gingerbread 2.3.5 for ATRIX 2 MB865 AT&T USA [Fastboot Files] - xda-developers
See this Guide for instruction on how to flash: xda-developers - View Single Post - UPDATE[12/31/11] The Beginners Guide !!! (NOOBS)
Scroll down to "How to flash a FXZ" for the step by step
Android 2.3.5 ---- Blur_Version.55.11.16.MB865.ATT.en.US
Gingerbread 2.3.5 for ATRIX 2 MB865 AT&T USA
See this post for a direct download link: [Fastboot Files] Gingerbread 2.3.5 for ATRIX 2 MB865 AT&T USA [Fastboot Files] - xda-developers
See this Guide for instruction on how to flash: xda-developers - View Single Post - UPDATE[12/31/11] The Beginners Guide !!! (NOOBS)
Scroll down to "How to flash a FXZ" for the step by step