Why won't my '99 Jeep Cherokee Sport start/fire? - related to draining battery?

Vehicle is a 1999 Jeep Cherokee Sport 4.0L in-line 6cyl with 100k miles. It has always fired up immediately and run fine. I parked it in the garage and left town for a few days. Upon returning I found the battery dead (lights NOT left on, and only accessory left on was the inoperable rear wiper - and POSSIBLY the under-hood illumination) and a buzzing sound (presumably an arc/short) coming from the Junction Box under the hood. I opened the junction box and wiggled the relays, etc. This affected the sound (better and worse) but could not make it stop. I gently rapped the noisy one with the box cover once and the sound stopped. I trickle-charged the battery and now the engine turns over great but will not fire, at all. Whatever short drained the battery seems to be preventing the engine from firing up. Fuel pump relay? I was pretty sure that wasn't the one I struck with the box-top to quiet the buzzing. Was running fine, as usual, when I parked it - no warning.