Re: E-99 won't fire
Yes, replace the battery with a new 9.6v and 180 -to- 220 mAh battery. Radio shack or other electronics store would have them.
also...the noid. Remove it and clean out any gunk in the clapper and polish the copper ring.
Check the board's capacitor (large black cylinder on top of the board). It should NOT be leaking any fluids and the ends of it should be absolutely flat. If either end seems like it's "bulging" (or it's leaking a dark fluid) it's bad and needs replacement. Again, radio shack has replacements.