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TPS65073 -- won't power off properly or turn back on

Other Parts Discussed in Thread: TPS65073, BQ27500

I'm trying to use the TPS65073, and when trying to turn it off I apparently can't get out of the state POWER OFF 3 from Figure 33 of the datasheet -- SYS is still powered and it won't turn back on unless I remove all power sources.

As shown in the figure below, the PB_IN node is pulled up (internally by the TPS65073) as soon as the battery is connected.  I do not have USB or AC power connected.  When I press the push button to ground the PB_IN node, SYS powers up (labeled SysPwr in the figure), the DCDC converters power on (shown is the 1.35 V rail turning on), and the POWER_ON signal coming up before the push button is released.  I am pleased with this power-on sequence.  I believe at this time (~1 second in the figure), I am in state POWER ON_1 from the datasheet Figure 33.

At time = 2.2 seconds, I drive POWER_ON low, the 1.35 V rail (driven off of DCDC3) turns off as it moves to the state POWER OFF 3.  However, SYS remains on, although my understanding is that it should turn off to conserve the battery.  At time = 4 seconds, I press the push button, and the system fails to turn on.   

I don't know why, but I'm guessing I'm stuck in state POWER OFF 3.  I can't be in the desired Power OFF state, where SYS is off, because SYS is on.  I can't be in Power OFF 2 state, because the push button doesn't turn it on.  Applying AC or USB power also doesn't turn it on, but if I unplug the battery, plug it back it, then apply AC power it does turn on.  I'm not using the LDOs, so I have left them open.  I get the same behavior after holding the push button for > 30 sec to reset the TPS and I removed the SD card so the micro couldn't boot and change anything.  I also get the same behavior if I let the micro boot and use it to disable the LDOs.

Any suggestions would be most appreciated.