I'm currently using Raspbian Jessie and I recently updated and ran
sudo aptitude upgrade it had a few things to upgrade and one removal which seemed normal.
During the upgrade, the display disappeared and the rainbow screen that appears briefly when the pi boots is all I get now.
The yellow light is flashing a few times in quick succession with a pause and then repeats. Any ideas how I can get the Pi to boot up, or get some error message out of it so I can post it here and/or search for a solution?