I've got exactly the same problem , car laid up for 4/5 years, no battery, cd changer works, mini disc works but radio is just static. Checked all aerial connections with a multimeter and all checks out, took aerial apart anyway and re sanded the earths etc, still no joy.
My dad who is a wizz at most things electric reckons it might be that the radio transistors need time to warm up to get working again, he's suggested runing the radio for 2 hours or so and see what happens - with no other ideas its worth a try.
Rob, August 2010