I have also experienced this when moving my CT63 between two Falcons. First check the pins on the expansion bus, it's very sensitive with correct contact. You can lift the card 1-2mm and test again. Next step is to test if there is any need to fix the reset loop. Hold the reset button and start the Falcon. Hold the reset for a couple of seconds and then release. Sometimes this wake up the CT63.
Atari Falcon, 14Mb RAM, CT60e, Supervidel, Svetlana, 512Mb RAM, 8Gb CF.
Atari Falcon, 14Mb RAM, CT63, 256Mb RAM,4Gb CF.
Firebee Series 2, 16Gb CF, 2Gb SD, MEGA ST Keyboard and Atari Mice.
Atari 2600 4-switch Woody