On your keyboard, inside that Serial console application (c-kermit in your case).
In log is written: "Hit Enter or space or Ctrl+C key to stop autoboot: "
And serial console is not just for upgrading, it will give you information about boot process and everything. if you dont press any keystrike it will boot normaly and give you bunch information over console .
with this new ROM here “reboot update” works to (VIM is in upgrade mode)
C:\platform-tools>adb shell
kvim:/ $ su
kvim:/ # ^D
kvim:/ $ reboot update
C:\platform-tools>
serial console log:
[ 665.949830@2] fb: osd[1] enable: 0 (surfaceflinger)
[ 934.535068@2] SysRq : Emergency Remount R/O
[ 934.545611@3] EXT4-fs (mmcblk0p13): re-mounted. Opts: (null)
[ 934.553064@3] EXT4-fs (mmcblk0p3): re-mounted. Opts: (null)
[ 934.554065@3] EXT4-fs (mmcblk0p8): re-mounted. Opts: (null)
[ 934.558591@3] Emergency Remount complete
[ 934.639553@0] avmute set to 2
[ 935.953238@2] aml_snd_card: no audio pin_ctrl to shutdown
[ 935.954266@0] vdin_drv_shutdown ok.
[ 935.956582@0] vdin_drv_shutdown ok.
[ 935.961867@0] fb: osd_shutdown
[ 935.963125@0] sysled: module shutdown ok
[ 935.967160@0] reboot: Restarting system(init) with command ‘update’
[ 935.974079@0] reboot reason 3