I populated a board with just one bq2002T, trying to charge one 9V battery.
It looks like it is a threshold problem with the combination of the bq2002t and the battery. If the battery doesn't fully charge past the 2V level it gets stuck in this mode (measuring pin 8 CC). I have made the theshold for these 9V batteries from 10.4 to 9.5 and always some batteries will get the BQ2002T stuck in this mode:
If the battery can charge higher it will get to trickle mode, but some batteries won't and the bq2002T will stay in this mode forever (well overnight anyway).
This test was done with only one of my six channels populated on the board. This is a really simple design and board shown below:
If I drain that battery a bit the bq2002T cc pin 8 will look correct at a constant 5V, but when the battery reaches the Vbat threshold it will go haywire. If I try a few different batteries some will charge to trickle and some won't.