Battery keeps dying and gauges bouncing everywhere

Hi guys,
Having an issue with my 2005 TJ Wrangler Sport (189000+ miles). I parked it about 2 months ago when I purchased a 2016 Wrangler as my daily driver. I would take my 05 out every now and then, and it ran fine. Couple of days ago, went to drive it, and the battery was dead. No big deal, it had sat for about 2 weeks, just needed a jump start. Got it jumped, started right up. As soon as I shut it off, battery was dead again. Jump started it again, drove it around the block a few times to charge up the battery, and that when I noticed the radio display kept flickering (it's a stock radio) and then the odometer started flickering. Got it back to the house (it ran fine) and shut it off. The gauges went nuts, the speedo and the tach needles were bouncing all over the place, and the battery was dead, wouldn't start. I pulled the battery out to put it on a trickle charger. I think the ECU/PCM might be shot. Any suggestions??

 

Finish the charge first, check connections, get the battery and alternator tested before suspecting the ECU.

 

Also physically clean all the battery connections 12+ on alternator and PDC. Clean all the grounds from battery to block block to frame, block to alternator and block to firewall. All of these connections need to bright shiny clean. Then get the battery load tested and have it checked for draw. You would be surprised at what conditions dirty connections and or a bad battery will cause.