Some time ago I retired a Stretch installation microSD that had been running on a Pi3b+. There was nothing wrong with it, I just wanted to upgrade the card and move to Buster. I saved the card to use as a test boot medium, since it had worked very reliably for a couple years.
However, when the card is inserted in a (somewhat older) pi3b (not a plus) the boot process sticks at the line "Started create volalatile files and directories" after which all progress seems to stop.
Is there some way to make the Pi boot to single-user mode?
All I really want to do run the vcgencmd to check if the boot from usb OTP is set. Still, it's puzzling that the card, which booted faultlessly in the 3b+, seems to be getting stuck in the older Pi.
Thanks for reading, and any ideas!
bob prohaska