Yes, you read that correctly. I plugged my monitor into my A2000 serial port (didn't have my glasses). Now it will boot off a floppy, but not the SCSI drive on the GVP card inside. I had used the A2000 about 3 weeks ago and every thing was fine. Do you think I burnt something out or was this just a random failure?
You might have fried one of the CIA-chips. Swap them out (your Amiga has two) to see if the error changes. If it does, you know for sure your CIA is fried. Replace it with a working one, presto.
As the CIAs are socketed in your A2000, this is a very easy and cheap repair. No soldering required, just pop out the defective chip and carefully put in a working one, done.