MC2500 tone remote failure troubleshooting

[maxjam]

I took a chance on 2 mc2500 units. One powers up and works great, the other just lights up and you can hear the relay pull in. After verifying the voltages were good, I swapped the bottom base with the working unit. The problem follows the top. The buttons don't light and nothing shows on the display so it appears that it isn't booting. Has somebody troubleshot a similar issue with the MC2500?

At least one is working.. sure is nice to have only 1 remote on the desk for my Cisco tone remote project!

Thanks