diff --git a/update_psa_impl b/update_psa_impl
index 3c96063..479e47d 100755
--- a/update_psa_impl
+++ b/update_psa_impl
@@ -71,34 +71,9 @@ update_psa() {
             
     update_psa_pull_customer_repository # message to ISMAS
 
-    # TODO: backup implementieren
-    # Backup before any updates in case some previous test was wrong
-    if ! backup_previous_version; then
-        log_error "$func:${LINENO}: backup failed"
-        revert_customer_repository
-        update_psa_backup_error  # message to ISMAS
-        exit $?
-    fi
+    # no backup necessary as saved in git-repo
     
-    update_psa_backup   # message to ISMAS
-
-    # TODO: use CLONE_CUSTOMER_REPOSITORY=true
-    # d.h. wird das rep geklont, also neu angelegt, dann sind eigentlich alle
-    # dateinen zu ueberpruefen
-
     local changed_files=$(changed_file_names)
-    local files_to_copy=$(filter_changed_files "$changed_files" 'json|ini|hex')
-
-    update_psa_report_changed_file_names $changed_files # message to ISMAS
-
-    # check if *.conf and/or *.ini-files have to md5-sum as denoted
-    # in update.conf
-    if ! check_md5_for_changed_json_and_ini_files "$files_to_copy" ; then
-        local __r=$?
-        log_error "$func:${LINENO}: new customer files wrong"
-        revert_customer_repository
-        exit $__r
-    fi
     
     if ! check_hardware_compatibility "$files_to_copy" ; then
         local __r=$?
@@ -107,14 +82,6 @@ update_psa() {
         exit $__r
     fi
         
-    # copy *.conf and/or *.ini-files to their corresponding system-directories
-    if ! copy $files_to_copy; then
-        local __r=$?
-        log_error "$func:${LINENO}: copy operation failed"
-        revert_customer_repository
-        exit $__r
-    fi
-    
     # check if the opkg-command-file has been changed during 'git pull'
     if grep -qE ".*opkg_commands.*?" <<< $changed_files; then
         # read opkg_cmds: each line respresents an opkg-command
@@ -164,9 +131,9 @@ update_psa() {
     fi
     
     # Cleanup.
-    if ! cleanup_previous_version; then
-        log_error "$func:${LINENO}: cleanup_previous_version failed"
-    fi
+    #if ! cleanup_previous_version; then
+    #    log_error "$func:${LINENO}: cleanup_previous_version failed"
+    #fi
 
     # compute version string for current (i.e. new) version
     compute_version