I just connected up a new to me HA yellow with an installed by me before power up an M2 drive
I went onto the HA site and the first page it starts with is the welcome home screen wanting a user name and password I cannot see how or where I can create these two items on this HA Yellow
HELP PLEASE
Hello FlyingScot
Welcome to the Home Assistant Forum!
Not sure what happened, but I would check here: Home Assistant Yellow - Home Assistant
or
I'm locked out! - Home Assistant
Just type your user name and password into those spaces and it will use those to create your account.
BUT I do NOT have a User Name or a Password set up YET!!
What @Arh means is that you can select your initial credentials yourself in this screen. Choose a name and password, enter it and you are good.
when i try to set up a serial connection using a GOOD USB type A to Type C Cable My laptop does not see the HA Yellow and when i slip in my iPhone to any of the three USB ports I get the beep and the message on my iPhone asking me to trust this computer with the HA yellow NOTHING!!!
Can we return to step 1?
Did you have a functional HA Yellow, to which you added a SSD? Or did you buy a used unit, added a SSD and then ran into the login problems?
Edit: if everything fails you can think about resetting the system.
i bought a used allegedly never used HA Yellow and before i did anything i put in the M2 drive
I have tried a HARD RESET as i have NO Data to loose and i removed the M2 drive and did another HARD RESET
Did you check that the jumper JP1 is set to UART?
YES it is set to UART
THE POWER LED IS ON SOLID the Yellow LED is blinking at a rate of blink blink blink and the one between it and the power LED flashes very quickly about every five yellow LED blinks and the CAT 5 connector LED is blinking as well
Well, obviously not 
The RPi4 is not the fastest machine. Putting on a SSD doesn’t mean that it is automatically used. It may well be that your system gets restored on the standard SD card.
So be patient, it will take some time.
User name cannot contain spaces and, I think, has to be lowercase.
lower case and no spaces in username made no difference remember I have never got to the input your username and password page
Well, if you don’t find a solution here: Home Assistant Yellow , I would strongly advice you to start from scratch as this would probably give you the fastest result.
that is what I thought so to keep things simple I removed the M2 drive and did a hard (factory) reset
Is it working now?
NOPE after 16 hours (overnight) the lights were still blinking
NOW Today after moving it and re powering it the yellow light was blinking a few times then went out BUT now when i try to access it http://homeassistant.local:8123/ it cannot be found
Hmm. We’re having trouble finding that site.
We can’t connect to the server at homeassistant.local.
The Yellow light is now out the power light is on and at the Enet socket the L/H led is constantly lit and the R/H Led is blinking
AND I thought that programming the HA yellow was going to be problematical
I am NOT a HAPPY BUNNY 
AND running out of ideas here
