Mac Pro 1,1 A1186 will boot and sleep, but not restart.
MacPro Original A1186 Dual-Core Intel Xeon
Diagnostic LEDs reflect no issue and the Mac is working fine until needing to restart rather than shutting down.
When restarting, as the mac powers down, there's a click from the optical drive resetting as the power cycles and it's here where it gets stuck - right before powering back up. At the same time the optical drives click, Diagnostic LEDs 2 & 3 flash briefly & the process repeats as the power cycles trying to restart.
Pressing the System reset switch doesn't yield a restart, rather inducing the problem and getting stuck. Strangely, getting stuck by way of the System reset switch results in a brief flash from Diagnostic LED 7 immediately after the flash from LEDs 2 & 3 which doesn't happen when simply restarting.
Removing the optical drives only quiet the issue as there are no drives to click, only Diagnostic LEDs 2 & 3 to flash. Apple Hardware Test returns no errors / have reset SMC / unable to zap PRAM.
Everything I can find online relates to fixing booting and start up issues, which all check out fine, including sleep. It's as though when restarting, the process isn't completing the power down or something drags and interferes with the powering back up.
Any help would be appreciated.