Weird boot issue

Hi all,I am in a great dilemma, when rebooting after agreeing to a software update, did not check the packges involved, but running Ubuntu 18.04, I was confronted with this:     GNU GRUB version 2.02Minimal BASH-like line editing is supported. For the first word, TAB listspossible command completions. Anywhere else TAB listspossible device or file completions.grub> _  ( flashing cursor)Don't know what to do here.I am running an ssd as sda,  sdb and sdc are in a btrfs RAID array.Puzzled by this behaviour.Any help appreciatedAndrew GreigSent from Samsung tablet.