Ubuntu MATE：无法访问 GRUB 菜单

我在 ThinkPad X200 上使用 Ubuntu MATE 16.04。出于某种原因，我无法在启动时访问 GRUB 菜单。当我shift在启动屏幕后立即点击时，GRUB loading（或类似的东西）短暂出现，然后我得到一个空白屏幕，然后正常的启动过程重新开始，我发现自己有正常的 LUKS 密码提示（我正在使用完整-磁盘加密）。

然后我尝试在 中禁用图形终端/etc/default/grub，但后来我得到error: no video mode activated了，它再次继续正常的启动过程。

这是我的/etc/default/grub文件的内容

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet systemd.unit=multi-user.target consoleblank=0"
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"