데비안 GUI가 시작되지 않았습니다

데비안을 부팅할 때 GUI가 시작되지 않습니다. 명령줄로 이동하여 로그인을 요청합니다.

andre@move-01:~$ systemctl status gdm3 service
* gdm.service - GNOME Display Manager
   Loaded: loaded (/lib/systemd/system/gdm.service; enabled)
   Active: active (running) since Mon 2017-01-09 13:32:21 BRST; 12min ago
  Process: 952 ExecStartPre=/usr/share/gdm/generate-config (code=exited, status=0/SUCCESS)
  Process: 952 ExecStartPre=/bin/sh -c [ "$(cat /etc/X11/default-display-manager 2>/dev/null)" = "/usr/sbin/gdm3" ] (code=exited, status=0/SUCCESS)
 Main PID: 958 (gdm3)
   CGroup: /system.slice/gdm.serivce
              958 /usr/sbin/gdm3
             1609 /usr/bin/Xorg :1 -novtswitch -background none -noreset -verbose 3 -auth /var/run/gdm3/auth-for-Debian-gdm-0Mifhr/database -seat seat0 -nolisten tcp vt7

* service.service
   Loaded: not-found (Reason: No such file or directory)
   Active: inactive (dead)

시도하면 sudo startx다음과 같은 결과가 나타납니다.

(EE)
Fatal server error:
(EE) Can't read lock file /tmp/.X0-lock
(EE)
(EE)
Please consult the The X.Org Foundation support
         at http://wiki.x.org
 for help.
(EE)
xinit: giving up
xinit: unable to connect to X server: Connection refused
xinit: server error

내가 시도한 다른 명령은 다음과 같습니다.

update-rc.d -f gdm defaults
sudo /etc/init.d/gdm3 stop && startx

어떻게 되어가나요?

(비슷한 질문이 있지만 그 중 어느 것도 나에게 적합하지 않습니다.)

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편집하다

출력 sudo journalctl -u gdm3:

-- Logs begin at Mon 2017-01-09 13:55:54 BRST, end at Mon 2017-01-09 14:25:33 BRST. --

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편집 2

lspci | grep VGA산출:

01:00.0 VGA compatible controller: Advanced Micro Devices, Inc.  [AMD/ATI] Tahi
 PRO  [Radeon HD 7950/8950 OEM / R9 280]