Did you just reinstall the old battery? Do you know if that battery is good?
Are you sure it's just 2 beeps? Error codes on the 4700 should come in 3 groups, separated by a brief pause.
So it you're getting 2 beeps-2 beeps-2 beeps, that would be a RAM error. Power off, unplug and press/hold power button for ~15 sec. Remove all RAM modules, except the one in slot 1 (closest to processor). Remove motherboard battery and press/hold power button for ~30 sec. Install a fresh battery and see if it boots now.
Then swap all modules into slot 1. If they all work alone in slot 1, add a module to second slot, reboot, add RAM to 3rd slot, reboot, etc until all RAM is installed to see if you might have a bum slot.
EDIT: Always power off, unplug and press/hold power button for ~15 sec before doing any work inside the case.
