hello Mohammad,
we have tried this and it failed. replaced web.comfig with one from Update Rollup (UR) 8 and was able to get to the login prompt. Came up with 404 error.
tried uninstalling CRM, failed.
Removed all UR's back to 6, changed web.comfig to a UR6 version.
Got another 404, make some changes, now at 401.
Trace files generated and now for more troubleshooting.