FANUC-controlled Quantum mill power failure, shut off by itself mid-cycle

Had two identical power failures on our FANUC 18M-controlled Quantum Q-1000V mill. Both failures occurred while in cycle on the same tool immediately after the tool change. Machine completely shut off at control box and the loud spindle fan also shut off, spindle continued to rotate under momentum until coming to a gradual stop. Neither the breaker on the machine nor the breaker on the wall tripped. Machine could not be restarted with the "ON" button, turning machine breaker off and on did nothing either. Turning off and on the wall breaker allowed the machine to be restarted. Alarms 350, 351, 414 and 749 present upon restart. Machine is currently functioning, not sure for how long. Any ideas on where to start?

It could be a wire has rubbed through in one of the flexible cable tracks. The normal spot is where the track meets the fixed cable tray, there is normally a sharp edge there. This is from my experience with a 2010 Quantum S1500D.

No breakers tripped but the spindle fan stopped? You mean the spindle motor fan, or a separate fan?

If it's a Fanuc spindle motor, and the spindle motor fan stopped, something tripped.

Everything electrical on the machine shuts off with zero warning. No breakers are tripped, the machine just needs to be turned back on again. The main breaker needs to be switched off and then back on, but is not tripped by the power failure. Yesterday it shut off as soon as I tried to home the Z axis. Restarted it and Z was able to be homed.

I ran a warm up program with coolant running for about an hour this morning, no issues. Shut it back down, power off, and have been checking every wire and connection I can find. Nothing is wet or damaged. Really boggles the mind. Will be lowering the Z as far as possible next, climbing up to the top and looking for any stretched or frayed wires. If I can't find anything I'll just start running parts again until it fails. Weird stuff.

I have had bad buss duct connections act that way.
Sound like an connection problem of some kind.

Sounds like a fault of the 5 volt power supply causing the computer of the machine to suddenly turn off.
Look up those alarm numbers you get after reset