USB 6210 reading impossible values or flatlining at -10V with RSE

[Daniel2]

I am using an NI USB-6210 with Matlab.  I have configured the analog inputs to be RSE and I have two inputs on ai0 and ai15. Ai15 is plugged directly into the board ground and I am touching the + terminal of an AA battery to ai0, briefely. When I look at my data, ai15 follows ai0 almost exactly, even though it is plugged directly into the board ground. Both inputs read all over  the place, from -10 to +10V.  I have the same results using the Measurement and automation explorer Test Panels. Furthermore, when it is not giving me outlandish results, +/- 8 volts from the AA or the board's +5V out pin, the analog ins flatline at -10.6V seemingly at random. Sometimes the values will drop slowly from some random value above -10V until they reach -10.6V and flatline.

I have reset, calibrated, and run self tests all after an ample warm up period.

Is my board dead or am I missing something huge?

[Dennis_Knutson]

For rse, you would connect ai0 to the + input and the board ground to the signal ground. I don't understand the point of connecting ai15. For a differential measurement, you would connect ai0 and ai8. Please look at the manual for connection information.

[Daniel2]

The idea with having ai15 connected to ground is that it should just read zero in RSE mode, but it reads the same as ai0 wich is touching the battery.

[Dennis_Knutson]

It seems you are taking a referenced measurement without a referenced and the input is floating. With the battery, you should be taking a differential measurement since you do not have it grounded.