I replaced the 9-volt batteries in all 3 of our hardwired smoke detectors, but all 3 continue to chirp about every 30-40 seconds. (note-these are new detectors I've just installed to replace ones that were 13 years old). (As per their instructions, I've pushed "test" before powering-up the circuit, which supposedly drained any residual voltage first). Checked the integrity of my wiring connections; all looks good. Think I have a bad detector(s) and should return it (them) to store? Thanks much, Jeff