Red light failures are usually faulty base function trays. Document PAA-2003-0305 Global. There is an updated document that's been release since then, but I can't find it at this point. Here's a snippet from that doc:
Recently, following reports from Nortel Networks distribution channels, a small percentage of field failures of the Business Communications Manager 3.0 in both the BCM 200 and BCM 400 systems was discovered. The characterization of these failures is an operational system failure with the red power LED remaining on and the inability to reset the system by either the reset button or a main power reset. After extensive testing in Nortel Networks labs, a component failure due to a process issue has been identified on the BCM motherboard, which causes the BCM system to go into a stand-by mode.
Call ITAS, open a case, and they'll RMA the tray for you.