If you find your MikroTik Router with an LCD display only displays a white back-light with a cross you may need to calibrate the display.
To calibrate the display press on the "x". The "x" will move to the next location on the display. Repeat until you receive and "calibration successful". You should now see a working display.
If you still see a white back-light display with the "x" again then it is quite possible a firmware upgrade will resolve the issue. To upgrade the firmware, first ensure you are running the latest RouterOS version and then in a "New Terminal" window enter the following (upgrade even if you are running the latest firmware to fix an potential corrupt firmware):
[admin@MikroTik] > system routerboard upgrade
Do you really want to upgrade firmware? [y/n]
firmware upgraded successfully, please reboot for changes to take effect!
[admin@MikroTik] > system reboot
Reboot, yes? [y/N]:
system will reboot shortly