Some additional info...
I'm running firmware 820000684_V (or at least that what last appeared before it went into this restart loop).
If I hook up a console cable and hold down the power button when rebooting and hit v, I go into a diagnostic start and it comes back with:
Watchdog test: okday
Serial Control Test: .000000
Serial Transmit Test: .000000
gpio-enet test: Interrupt not detected
Memory test: okay
mbox test: processor 0 okay
Ethernet: Internal Selftest Failed (0xfffffff)
PHY reset failed
RTC test: OK
Rebooting to Correct PCI Issue
(And it just loops here)
If I hold down a key, when all of this is happening, I can get a diagnostic menu to come up for a short while, but it then cuts off and reboots again. The only additional info is that it says:
Boot Revision 82000685_G 02/02/2006 which is interesting, since previously it said 820000684_V the last time I was able to connect to it before the restart)
Even when I bring up the diagnostic menu, I can't get a chance to enter anything, it just starts displaying the menu and the cuts off and reboots.