What is the problem?
I have two Raspberries (1 and 3B+), and I have never done anything on Raspi before.
I downloaded the most current OctoPi image last week and used balenaEtcher to copy it to an 8GB microSD Card. Then I tried it on my 3B+. The LEDs blink, there are several pages of boot log shown on the monitor (too fast to read, but the last line I can read is "Started Login Services" most of the time. Sometimes the last line is something with LSB)), and then the monitor gets dark again, and it all starts again, and again and .. you get the picture.
What did you already try to solve it?
I put the microSD card in an SD-Card adapter and tried it on my Raspi 1, to make sure that it is not a faulty image or card. And I see the same log information, and after some time, I get to the point where I am asked for username and password (which I have not yet changed), and after that, I get a normal
So it seems, the image is OK, right?
Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, what kind of hardware precisely, ...)
OctoPi Buster Lite 0.17.0#
Raspberry 1373331 Pi 3 Modell B+ Mainboard, 1 GB