Somehow I managed to mess my Yellow up. I decided to do a fresh install. The hardware is Yellow with CM4, no nvme.
I began with erasing the os by holding down the blue and red buttons while applying power, holding the buttons down for 15 seconds.
I then removed power, inserted the flash drive prepared with rpi imager, plugged in the network connection and powered it on.
First, the light on the flash drive lit, then the red and yellow light flashed alternately. After about 2 or 3 minutes, the red and yellow lights remain lit with the green light flickering about every 5 seconds.
Have I bricked it?