Good!
If you get to the Utilities screen, the terminal is available from the top menubar. It is not in the menu window, but the menubar at the top of the screen
So, the memory sticks aren't cooperating too well for you.
Best to remove all, and insert again. Do this a couple of times for each stick, so you have a good "feel" for how much pressure it takes to seat completely. It's actually quite a lot of "push", and if it is not seated properly, you WILL get the beeps, etc.
However, you may have another problem, which may be much more serious.
Often, when a Mac just shuts down, after you see the progress bar for a couple of minutes, no progress, then simply shuts off (?)
That is often an indication that the hard drive is failing, or already failed.
I hope you have a backup of your important files/pictures, etc.