BQ25792EVM: not getting results I understand

I tested your register file into a BQ25792 EVM and it works fine. The inline amp meter might be causing issues with it's series resistance. Have you tried removing the current meter?

By the way, I would advise against setting VSYSMIN higher than the charging voltage. Once the voltage input is disconnected, the battery charger will not be able to sustain VSYSMIN and the voltage will fall to the battery voltage.

I did remove the amp meter and the results are the same. Once I remove VAC, I can no longer communicate with the device, so this means i2c is not functioning when on batt power?  All in all this looks very fishy, smells like a busted chip to me!

I see. I don't think the chip is busted yet. It maybe the input mosfets. Can you short jumper JP3? This will connect VAC1 directly to VBUS and bypass the input mosfets.

I've spent another day poking at this thing, VAC bridged or not, using input 1 vs 2, nothing makes sense of the data I am seeing. As a matter of fact the chip now reads voltages that are below 2.5Volt (Vsys, VBatt) even though it is powered by a nice steady 5.2V/3A on VAC input and a 3.8V 18650 in place. Seems this chip is toast indeed. Nice!  What a waste.

Right, I purchased this directly from TI, anyway this can be returned & replaced?

There's a few more tests that need to be run before that.

Can you send a picture of the board so I can check to make sure the jumpers are in the right place?

With battery only attached, does BAT TP measure the correct battery voltage? If so, does SYS = BAT? If that is true, can you communicate via I2C?

If you can communicate via I2C, don't change an registers and attach VBUS. Can you measure switching at SW1 or SW2?

Without Vac connected, according to the BQ25792, Vbat is sitting at 3.79 volt and Vsys at 3.76. A DVM shows 3.81 measured at the battery. Without Vac input I2C is functional.  I am not getting the chip to charge the battery (even though the LED is on), in fact the battery is slowly discharging through the EVM. Picture  of EVM is attached.

Your jumpers are in the right position. When you attach VBUS, can you measure switching at SW1?

With no power applied, can you also measure the resistance between VBUS to GND, REGN to GND, PMID to GND, VBAT to GND, and SYS to GND?

With VBUS connected and a mostly charged batt installed, SW1 is at a constant 2VDC. Without a battery or a mostly discharged battery, SW1 switches between 0 and 2VDC in somewhat irregular intervals of 600ms - what is this signal supposed to look like?

Without VBUS nor battery installed, R values are:

VBUS - GND: not getting a solid R reading. Something is charging/discharging, R reading between 500k and several meg

REGN - GND: 4k7

VBAT - GND: 31E

SYS - GND: infinity / very high.

By 31E, do you mean 31 ohms?

yes

Thanks, I sent you some of the packing list info you may need in a PM.