There is a post, search for bootloader. You can download the tools.rar file and it has a script with the lock, fuse settings and the bootloader.hex file.
You need the correct fuse settings to set the clock from the crystal.
The firmware and bootloader need flashing if you erase the chip using a icsp programmer.
If you get stuck, ive ended up with a few spare 1284p and can send you a programmed one, but following the settings in the bat file will create a working chip.
All led on at power on?
Link to tools.rar here viewtopic.php?f=25&t=1141&p=7130&hilit=Tools.rar#p7130
Thanks for your reply. 
Fortunately I went on the forum, otherwise I would never have known all that.orbist wrote:A few things I wasted time on.
You will measure continuity (400 and 1800 in each direction) between 15v and -15v if you have ANY M5218L soldered in the analog section. I soldered the ones in the noise section before I started socketing them. I discovered this by cutting all the RP links and tracking it back to them. If you try a continuity test on a chip on its own you get the above measurements.
In the sequencer section you will measure continuity between gnd and 5v if nothing connected Box à Louer. This seems to be the flow of the continuity test current across the capacitors in the section. If you test between and of them you get the same.
Not being an expert, I spent time chasing these and it seems normal. When powered up, your 5v, and 15v will measure perfect. So this all seems normal.