]The cross-posting will not happen.
Probably dead. Put a new battery in. While you are at it, use a real battery. 9V batteries are for smoke detectors.
That is what I thought (the same battery was used for a few weeks). However, after changing it, it didn't work.
I tried 6 fully charged AA for the Uno while the 7.2V was connected to the motor board, and nothing..
while the motor board is attached, the 3.3V and 5V reads 0.8V. When the motor board is not attached, I read 2.86V.
This just seems weird because it has been working for a few weeks now, and sometimes I wouldn't even have the 9V battery connected the UNO, just the 7.2V to the motorboard (which would run both).
Also,
While you are at it, use a real battery.
, what do you consider a "REAL" battery that could be used?