50-50 chance I reckon. 3.3V regulators do odd things with floaty grounds.
I'm not convinced having a separate power supply is a great idea for floppies. On an A2000 at any rate.
It's not like AmigaDos uses more than 2 floppy drives at a time, and that's just for copying a whole disk from one to the other. Generally only one is in use for reading. Depends how quick you eject and insert disks mostly.
As a rule of thumb, I turn on external expansions before powering up the Amiga.
External floppies going pear shaped can damage pull up resistors on the floppy circuitry. Usually the problems start by the power to the external floppy being shorted out with a different connector.
You have to allow yourself to make mistakes and learn from them with renovation.
Anyhow, if you start with getting DF0: internally working, you can use the external port to "snoop" on the different signals with a logic probe. In that case, having no power on the external floppy port actually works in your favor.
I figured out how this happened. I was using the unit just fine with the floppy gotek setup. BUT I plugged a second gotek into the rear port forgetting it was one I got somewhere that has a cut off freaking connector that you have to make sure is moved to the side because it just has two pins cut off.. Was not paying attention and that was it. poof.
Pisses me off though as I should have probably found a new connector instead of just trusting to remember to plug it in the right way due to this one was made for the external connector.
Going to order a new connector and replace the one on this other one so I don't do this again.
BTW, do you know a good source for parts like this or the fuses I will need to replace? F4 is blown, F3 tests fine.
