About the floppy: can you try with a Gotek emulator drive to see if the problem is the drive or something else? In the past, a drive of mine stopped to work suddenly, another started act like "I work when I want", etc.).
About the yellow screen: accordingly with the Error color scheme, "Chance screen colour to Yellow if there is an error with external cards/devices."
Take a look at:
https://www.lemonamiga.com/forum/viewtopic.php?t=13978
