I was playing with a theme (Atolm-GS) and followed the install instructions which stated to back up the /usr/share/gnome-shell/theme directory, and replace it with the one from the theme. I did this, logged off, logged on, got my wallpaper for a second, then the Oh No Screen. I logged off, logged in to IceWM, replaced the theme folder with the original, logged back in to Gnome3 and same thing. Alt+F4 does not get rid of the OH No screen.
My ~/.xsessions-errors file contains the following:

/etc/X11/xim: Checking whether an input method should be started.
sourcing /etc/sysconfig/language to get the value of INPUT_METHOD
INPUT_METHOD is not set or empty (no user selected input method).
Trying to start a default input method for the locale en_US.UTF-8 ...
There is no default input method for the current locale.
Dummy input method "none" (do not use any fancy input method by default)
gnome-session[4649]: WARNING: Could not parse desktop file /etc/xdg/autostart/ksmolt-autostart.desktop: Invalid key name: X-KDE-autostart-condition[$e]
gnome-session[4649]: WARNING: could not read /etc/xdg/autostart/ksmolt-autostart.desktop

** (gnome-settings-daemon:4733): WARNING **: Ignoring unknown module 'org.gnome.settings-daemon.plugins.gconf'
GNOME_KEYRING_CONTROL=/tmp/keyring-m36Sg0
GPG_AGENT_INFO=/tmp/keyring-m36Sg0/gpg:0:1
GNOME_KEYRING_CONTROL=/tmp/keyring-m36Sg0
GPG_AGENT_INFO=/tmp/keyring-m36Sg0/gpg:0:1
GNOME_KEYRING_CONTROL=/tmp/keyring-m36Sg0
GPG_AGENT_INFO=/tmp/keyring-m36Sg0/gpg:0:1
SSH_AUTH_SOCK=/tmp/keyring-m36Sg0/ssh
GNOME_KEYRING_CONTROL=/tmp/keyring-m36Sg0
GPG_AGENT_INFO=/tmp/keyring-m36Sg0/gpg:0:1
SSH_AUTH_SOCK=/tmp/keyring-m36Sg0/ssh

(gnome-settings-daemon:4733): PackageKit-WARNING **: failed to set proxy: failed to obtain auth

(gnome-settings-daemon:4733): updates-plugin-WARNING **: failed to set proxies: failed to obtain auth
Initializing tracker-store...
Tracker-Message: Checking XDG_DATA_HOME is writable and exists
Tracker-Message: XDG_DATA_HOME is '(null)'
Tracker-Message: Path is OK
Tracker-Message: XDG_DATA_HOME set to '/home/mike/.local/share'
Tracker-Message: Path is OK
Tracker-Message: Setting up monitor for changes to config file:'/home/mike/.config/tracker/tracker-store.cfg'
Tracker-Message: Loading defaults into GKeyFile...
Tracker-Message: Setting up monitor for changes to config file:'/home/mike/.config/tracker/tracker-db.cfg'
Tracker-Message: Loading defaults into GKeyFile...
Tracker-Message: Log verbosity is set to 0, disabling D-Bus client lookup
Starting log:
File:'/home/mike/.local/share/tracker/tracker-store.log'
Initializing tracker-miner-fs...
Tracker-Message: Checking XDG_DATA_HOME is writable and exists
Tracker-Message: XDG_DATA_HOME is '(null)'
Tracker-Message: Path is OK
Tracker-Message: XDG_DATA_HOME set to '/home/mike/.local/share'
Tracker-Message: Path is OK
Tracker-Message: Setting process priority
Tracker-Message: Setting up monitor for changes to config file:'/home/mike/.config/tracker/tracker-miner-fs.cfg'
** Message: applet now removed from the notification area
liblazy (liblazy_dbus_send_method_call:97): Received error reply: The name org.freedesktop.Hal was not provided by any .service files
liblazy (liblazy_hal_get_strlist_manager:122): Error while sending method FindDeviceByCapability to HAL
ERROR (gd_dbus_get_dock:36) Error looking for dock device
INFO (main:38) No docking station detected, exiting...

Failed to play sound: File or data not found
Starting Dropbox...
(gnome-settings-daemon:4733): updates-plugin-WARNING **: failed to open directory: Error opening directory '/run/udev/firmware-missing': No such file or directory
lpstat: No destinations added.
Tracker-Message: Loading defaults into GKeyFile...
Starting log:
File:'/home/mike/.local/share/tracker/tracker-miner-fs.log'
JS ERROR: !!! Exception was: Error: FIXME: Only supporting null-terminated arrays of strings
JS ERROR: !!! lineNumber = '0'
JS ERROR: !!! fileName = 'gjs_throw'
JS ERROR: !!! stack = '("FIXME: Only supporting null-terminated arrays of strings")@gjs_throw:0
()@/usr/share/gnome-shell/extensions/xrandr-indicator@gnome-shell-extensions.gnome.org/extension.js:72
()@/usr/share/gnome-shell/extensions/xrandr-indicator@gnome-shell-extensions.gnome.org/extension.js:61
Indicator()@/usr/share/gnome-shell/extensions/xrandr-indicator@gnome-shell-extensions.gnome.org/extension.js:41
()@/usr/share/gnome-shell/js/ui/panel.js:1051
start()@/usr/share/gnome-shell/js/ui/main.js:204
@<main>:1
'
JS ERROR: !!! message = 'FIXME: Only supporting null-terminated arrays of strings'
Window manager warning: Log level 32: Execution of main.js threw exception: Error: FIXME: Only supporting null-terminated arrays of strings

(nm-applet:4787): libnotify-WARNING **: Failed to connect to proxy
gnome-shell-calendar-server[4839]: Got HUP on stdin - exiting
Dropbox isn't running!
Done!
JS ERROR: !!! Exception was: Error: FIXME: Only supporting null-terminated arrays of strings
JS ERROR: !!! lineNumber = '0'
JS ERROR: !!! fileName = 'gjs_throw'
JS ERROR: !!! stack = '("FIXME: Only supporting null-terminated arrays of strings")@gjs_throw:0
()@/usr/share/gnome-shell/extensions/xrandr-indicator@gnome-shell-extensions.gnome.org/extension.js:72
()@/usr/share/gnome-shell/extensions/xrandr-indicator@gnome-shell-extensions.gnome.org/extension.js:61
Indicator()@/usr/share/gnome-shell/extensions/xrandr-indicator@gnome-shell-extensions.gnome.org/extension.js:41
()@/usr/share/gnome-shell/js/ui/panel.js:1051
start()@/usr/share/gnome-shell/js/ui/main.js:204
@<main>:1
'
JS ERROR: !!! message = 'FIXME: Only supporting null-terminated arrays of strings'
Window manager warning: Log level 32: Execution of main.js threw exception: Error: FIXME: Only supporting null-terminated arrays of strings
ERROR:dbus.proxies:Introspect error on :1.50:/org/freedesktop/Notifications: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Message did not receive a reply (timeout by message bus)
gnome-session[4649]: WARNING: App 'gnome-shell.desktop' respawning too quickly
gnome-shell-calendar-server[4936]: Got HUP on stdin - exiting

Any ideas on how to fix or go back to default theme? I already tried reinstalling Gnome3 stuff and no change.
Thank you in advance