Hello Michael
I know its been a while since you posted but I thought I'd comment.
Red and Green flashing means the whole system has restarted - like after a power on.
If it stays like that it means the Raspberry Pi hasn't started - and that can be a hardware fault - we typically suggest replacing the SD card first because that often works and its easy.
In your case because you had an external hard disk attached it may be to do with the power consumption by the external disk - so take that out as a first step.
What I would also like to say is that "wiping the hard disk" doesn't happen.
I mean even when owners have formatted the internal hard disk - we have recovered the music.
There are many faults that could make the music inaccessible and require our intervention - but unless the disk breaks down the music is still there.
Martin