Help me please. Error: 'git checkout' failed git-crypt has been set up but existing encrypted files have not been decrypted.

I have checked out my branch and tried to decrypt it's data, but got the error mesage:

```
Error: 'git checkout' failed
git-crypt has been set up but existing encrypted files have not been decrypted
```

Here is the steps that led up to it.

```
git checkout -b wnr2200_Flat4 origin/wnr2200_Flat4

Branch wnr2200_Flat4 set up to track remote branch wnr2200_Flat4 from origin.
Switched to a new branch 'wnr2200_Flat4'
```

```
git pull

Already up-to-date.
```

```
git-crypt status

not encrypted: .git-crypt/.gitattributes
not encrypted: .git-crypt/keys/default/0/B8F91A7C454C712DAF8CAD6A4C7B8EA505CF6FE4.gpg
not encrypted: .gitattributes
not encrypted: .gitignore
not encrypted: archives/backup-2Lv-dn-2015-02-21.tar.gz
not encrypted: archives/backup-2Lv-up-2015-02-25.tar.gz
not encrypted: archives/backup-3Lv-2015-02-25.tar.gz
not encrypted: archives/backup-4Lv-2015-02-25.tar.gz
not encrypted: archives/backup-Bungalow-2015-02-25.tar.gz
not encrypted: archives/backup-Flat1-2015-02-25.tar.gz
not encrypted: archives/backup-Flat4-2015-09-22_initial-upload-bef-chg-root-pwd.tar.gz
not encrypted: archives/backup-Flat4-2015-09-22_w-chgd-root-pwd.tar.gz
not encrypted: archives/backup-Flat4_blank_192.168-2015-09-22.tar.gz
not encrypted: archives/backup-Flat5-2015-02-25.tar.gz
not encrypted: archives/backup-Flat6-2015-02-25.tar.gz
not encrypted: archives/backup-Flat7-2015-02-25.tar.gz
not encrypted: archives/backup-Test_AP-2015-02-25.tar.gz
not encrypted: etc/config/dhcp
not encrypted: etc/config/dropbear
not encrypted: etc/config/firewall
not encrypted: etc/config/luci
not encrypted: etc/config/network
not encrypted: etc/config/rpcd
not encrypted: etc/config/system
not encrypted: etc/config/ubootenv
not encrypted: etc/config/ucitrack
not encrypted: etc/config/uhttpd
encrypted: etc/config/wireless
not encrypted: etc/dnsmasq.conf
encrypted: etc/dropbear/dropbear_dss_host_key
encrypted: etc/dropbear/dropbear_rsa_host_key
not encrypted: etc/firewall.user
not encrypted: etc/group
not encrypted: etc/hosts
not encrypted: etc/inittab
not encrypted: etc/opkg.conf
not encrypted: etc/passwd
not encrypted: etc/ppp/chap-secrets
not encrypted: etc/ppp/filter
not encrypted: etc/ppp/options
not encrypted: etc/profile
not encrypted: etc/protocols
not encrypted: etc/rc.local
not encrypted: etc/services
encrypted: etc/shadow
not encrypted: etc/shells
not encrypted: etc/sysctl.conf
not encrypted: etc/sysupgrade.conf
encrypted: etc/uhttpd.crt
encrypted: etc/uhttpd.key
```

Then I thought this woudl be the right thing to do, but maybe it wasn't?

```
git-crypt unlock ~/git-crypt-mykey.key

git-crypt: error: encrypted file has been tampered with!
error: external filter "git-crypt" smudge failed 1
error: external filter "git-crypt" smudge failed
fatal: etc/config/wireless: smudge filter git-crypt failed
Error: 'git checkout' failed
git-crypt has been set up but existing encrypted files have not been decrypted
```

And now I suddenly have **6 changed files**. (and if I peek into them they all have '^@GITCRYPT^@' at the start of the file.)

```
git status

On branch wnr2200_Flat4
Your branch is up-to-date with 'origin/wnr2200_Flat4'.
Changes not staged for commit:
(use "git add/rm ..." to update what will be committed)
(use "git checkout -- ..." to discard changes in working directory)

deleted: etc/config/wireless
modified: etc/dropbear/dropbear_dss_host_key
modified: etc/dropbear/dropbear_rsa_host_key
modified: etc/shadow
modified: etc/uhttpd.crt
modified: etc/uhttpd.key

no changes added to commit (use "git add" and/or "git commit -a")
```

How do I recover from this?